2pm (11pm JST): Here's a summary of events so far today:

• A "core meltdown" might have occurred at reactor 2 Fukushima Daiichi. NHK World reports, as fears grow over the safety of the nuclear plant continues. Fuel rods are reportedly fully exposed. The nuclear and industrial safety agency (NISA) has tried to circulate the coolant by steam instead of electricity, but NHK reported that attempts to lower the temperature inside the reactor chamber have not worked well. NISA is reportedly also considering opening a hole in the reactor housing building to release hydrogen generated by the exposed fuel rods.

• A hydrogen explosion at the number 3 reactor at the Fukushima No 1 nuclear injured 11 people. The blast had been anticipated and was similar to the explosion seen previously at the number 1 reactor. It has not, apparently, damaged the reactor itself or the containment vessel and authorities said radiation levels were normal around it.

• Police are reporting that about 1,000 bodies have been found in Minamisanriku and another 1,000 on the Ojika Peninsula coast in Miyagi. Miyagi has been the worst hit prefecture. Video footage is continuing to emerge revealing the force of the tsunami that swept into north east Japan.

• Plans for rolling black outs in Tokyo and the surrounding area are currently suspended. Many private firms have voluntarily halted business or taken other measures to help reduce demand; although supply has been hit badly by the nuclear plant closures, it is still keeping up with consumption at present.
Other countries have been reviewing their nuclear programmes in the light of events in Japan. Switzerland has suspended plans to replace and build new nuclear plants and Germany is expected to is expected to announce the suspension of plans to extend the life of its nuclear power stations later today.

Click here to read the previous Guardian blog charting the day's events so far.

2.13pm (11.13pm JST): Justin McCurry, the Guardian's Tokyo correspondent, emails to say the water level inside the No. 2 reactor at Fukushima Daiichi nuclear power plant has recovered to a level of about two metres, according to Kyodo News. The rods were fully exposed for about two and a half hours, according to Japan's Nuclear and Industrial Safety Agency.

2.28pm (11.28pm JST): My colleagues Dan Chung and Laurence Topham have produced this video combining images of the destruction in Miyagi with the testimony of a survivor of the Japanese tsunami: .

2pm (11pm JST): Here's a summary of events so far today:

• A "core meltdown" might have occurred at reactor 2 Fukushima Daiichi. NHK World reports, as fears grow over the safety of the nuclear plant continues. Fuel rods are reportedly fully exposed. The nuclear and industrial safety agency (NISA) has tried to circulate the coolant by steam instead of electricity, but NHK reported that attempts to lower the temperature inside the reactor chamber have not worked well. NISA is reportedly also considering opening a hole in the reactor housing building to release hydrogen generated by the exposed fuel rods.

• A hydrogen explosion at the number 3 reactor at the Fukushima No 1 nuclear injured 11 people. The blast had been anticipated and was similar to the explosion seen previously at the number 1 reactor. It has not, apparently, damaged the reactor itself or the containment vessel and authorities said radiation levels were normal around it.

• Police are reporting that about 1,000 bodies have been found in Minamisanriku and another 1,000 on the Ojika Peninsula coast in Miyagi. Miyagi has been the worst hit prefecture. Video footage is continuing to emerge revealing the force of the tsunami that swept into north east Japan.

• Plans for rolling black outs in Tokyo and the surrounding area are currently suspended. Many private firms have voluntarily halted business or taken other measures to help reduce demand; although supply has been hit badly by the nuclear plant closures, it is still keeping up with consumption at present.
Other countries have been reviewing their nuclear programmes in the light of events in Japan. Switzerland has suspended plans to replace and build new nuclear plants and Germany is expected to is expected to announce the suspension of plans to extend the life of its nuclear power stations later today.

Click here to read the previous Guardian blog charting the day's events so far.

2.13pm (11.13pm JST): Justin McCurry, the Guardian's Tokyo correspondent, emails to say the water level inside the No. 2 reactor at Fukushima Daiichi nuclear power plant has recovered to a level of about two metres, according to Kyodo News. The rods were fully exposed for about two and a half hours, according to Japan's Nuclear and Industrial Safety Agency.

2.28pm (11.28pm JST): My colleagues Dan Chung and Laurence Topham have produced this video combining images of the destruction in Miyagi with the testimony of a survivor of the Japanese tsunami:

2.37pm (11.37pm JST): On the old live blog user reinvertthatpyramid writes:

At the top of the page in your summary you state that plans for rolling black outs are currently suspended. However I am sat in front of my TV in my apartment just outside of Tokyo and they are running through the black out times and areas for tomorrow. They include all areas of Tokyo except very central and all surrounding prefectures.

We'll try and confirm that this afternoon.

2.43pm (11.43pm JST): Haroon Siddique has been rounding up some of the video footage online following the earthquake and tsunami in Japan: including this video which shows water cascading across fields and towns.

You can read Haroon's piece here.

2.49pm (11.49pm JST): The Guardian's live Q&A will continue again from 3pm, with Prof Keith Ross from the University of Salford joining the thread.

Ross is a part of the the Material and Physics Research Centre and is an expert on radiation damage to materials.

You can leave your questions for Ross here.

3.11pm (12.11am JST): Fuel rods are fully exposed again at Fukushima, according to Kyodo news agency. The rods are usually submerged in several metres of water to stop them overheating, however this morning the rods in reactor 2 were completely exposed this morning.

Reactor workers have been attempting to pump seawater around the rods, however they do not appear to be having much success if Kyodo is to be believed.

3.24pm (12.24pm): My colleague Laura Oliver has been following the Guardian's live Q&A on the Japan nuclear crisis. (The Q&A is continuing at the moment if you want to post a question).

Professor Gerry Thomas, who holds a chair in molecular pathology at Imperial College London, began proceedings by pointing out that "one thing to note is that there has not yet been a significant release of radiation from this nuclear plant - the reactor core is currently still intact". Thomas's responses to Guardian readers' questions are in grey below:

The radioactive element that would do most damage to the health of the population would be radioiodine, which in certain circumstances can give rise to thyroid cancer, particularly when exposure is to young children. However, we are far from this in Japan at present.

• User rickhartland asked Thomas what levels of radiation exposure are likely to affect the elderly and vulnerable, and what preventative measures could be taken.

Let us get one thing straight - at present there has not been a significant release of radiation. It is impossible to hide this release. Even if the reactor were to explode (which is very unlikely) the release would be unlikely to lead to sufficient dose to cause radiation sickness - you need very high levels of whole body radiation to cause this. Young people (children in particular) are more susceptible to the effects of radiation. With regard to your third point, no-one needs to be concerned about this at present as there has been no significant release of radiation.

• User Bluecloud asked if iodine does help against radiation poisoning and if so, when should it be taken?

Yes you do need to take stable iodine before exposure - if taken after exposure it can effectively lock in any radioactive iodine that has been absorbed.

• User assaultedpeanut, who lives in Tokyo, said people there are beginning to head west due to fear of radiation travelling south from Fukushima. "I feel that this is mostly coming from sheer panic," assaulted peanut said, "But I would like to know an expert's view on how likely it is for this to happen."

There has been very little release of radiation and there is unlikely to be a significant release. My advice would be not to worry. You are lucky because in Japan you eat a diet that is rich in iodine - this would protect you from the worst possible effects. I would not advise you to do anything further unless instructed by your government or medical authorities. I am afraid there is far too much scaremongering!

3.29pm: Japanese officials say the nuclear fuel rods appear to be melting inside all three of the most troubled nuclear reactors, according to Associated Press.

Chief Cabinet Secretary Yukio Edano said: "Although we cannot directly check it, it's highly likely happening."

3.51pm: David Cameron has offered his condolences to the Japanese people, telling the House of Commons "we were all deeply shocked by the devastation we have seen and the loss of life".

My colleague Andrew Sparrow followed the prime minister's statement live from Westminster:

Cameron said that as yet, there are no confirmed British fatalities. But the government has "severe concerns" about some Britons.

Three teams of British officials are working in the disaster area. A helpline has been set up for families who are worried.

Humanitarian assistance has been offered to the Japanese. A 63-strong rescue team has been despatched to Japan from the UK.

The Japanese government are doing everything they can to manage the problems at the nuclear reactors.

Chris Huhne, the energy sector, has commissioned a report on the implications for the nuclear industry in the UK.

Cameron says the devastation has been terrible. We do not know the death toll. But Japan is a resourceful nation. It will recover.

4.10pm GMT: The Guardian's live Q&A on the Japan nuclear crisis continues, with answers from Professor Keith Ross of the Material and Physics Research Centre at Salford University, who is an expert on radiation damage to materials.

User bluecloud asks where the hydrogen reported in the explosions at the nuclear plants is coming from? Prof Ross replies:

The explanations in the press of where the hydrogen originates are somewhat divergent. I don't believe that it can come from the thermal decomposition of steam alone because the oxygen and hydrogen would be fully mixed in the gas phase and would just recombine as the temperature drops. The suggestion that the steam reacts with the zirconium (zircalloy) cladding to form the oxide (which is very stable) and that this leaves much purer hydrogen seems much more convincing. Another way of looking at this is to consider the thermal decomposition of steam followed by the extraction of the oxygen to form the oxide – again leaving pure hydrogen.

Question from contractor000 asks about the use of sea water to cool the system and how this works:

Re emergency use of salt water cooling, this is presumably being pumped through the ECC (emergency core cooling) system that would normally spray pure water onto the exposed fuel elements inside the pressure vessel. The resulting steam will have to be allowed to escape from the pressure vessel if the pressure inside begins to rise dangerously. Normally, hot water would be pumped from the bottom of the core but presumably this is not working. Salt water will not do the core much good as it is much more corrosive than pure water.

Incidentally, for the record, all the detailed calculations show that, after you allow for "renewable obligation etc", nuclear power is cheaper than renewables with the exception of hydropower in a prime location. Also, it is normally assumed that the tritium for a fusion reactor will have to come through breeding it in the Li blanket. The present source – the D2O moderator of CANDU reactors would not be able to keep up with any significant deployment of fusion power.

Prof Ross responds to rooster1981 who asks about the heat within the reactors - how hot are the fuel rods now since the fission reaction was halted on Friday afternoon?

Just to be clear about the heat being generated after the fission process has been shut down, it is due to the nuclear decays of the fission products – the atoms with mass about half that of uranium produced in fission – which then decay by either emitting electrons or gamma rays. Each of these individual isotopes decays with its own unique half life - ie, it goes down to half its intensity after one half life, 1/4 after two etc. But when you add all these together, it cools down as a power law. It starts at about 7% of the total power but is down to 1% after an hour (DoE text)

This is Richard Adams in the Guardian's Washington bureau taking over live blogging for the next few hours.

4.29pm GMT: The Associated Press is quoting a Japanese government official as saying the possibility of damage to one of the nuclear containment vessel at the Fukushima Daiichi plant cannot be ruled out:

"It's impossible to say whether there has or has not been damage" to the vessels, nuclear agency official Naoki Kumagai said.

So far this evening Japanese officials have said that the fuel rods in all three of the most troubled nuclear reactors appeared to be melting, and that the drop in water levels at Unit 2 had officials the most worried:

"Units 1 and 3 are at least somewhat stabilized for the time being," said Nuclear and Industrial Agency official Ryohei Shiomi "Unit 2 now requires all our effort and attention."

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4.41pm GMT: London's Evening Standard newspaper leads the way with a headline that manages to be trivial and panic-inducing at the same time, as my colleague Stuart Millar tweets.

5.07pm GMT: The US Nuclear Regulatory Commission has announced that the Japanese government has formally asked the US for assistance with cooling nuclear reactors. The head of the Nuclear Regulatory Commission says it is responding to the request and considering providing Japan with technical advice.

(On Friday, US secretary of state Hillary Clinton said the US military was supplying coolant to the Japanese authorities, but that turned out to be a mis-statement.)

At a White House briefing right now, it was stated that the US government was in close consultation with its Japanese counterparts, and sharing information, and has sent reactor experts to help.

5.12pm GMT: The White House briefing continues. On the state of the Fukushima reactor cores, the spokesman for the US department of energy says: "We don't really have detailed information."

5.23pm GMT: The Guardian has compiled a full list of nuclear power plant accidents since 1952 over at the Guardian's Datablog:

We have identified 33 serious incidents and accidents at nuclear power stations since the first recorded one in 1952 at Chalk River in Ontario, Canada.

The information is partially from the International Atomic Energy Authority - which, astonishingly, fails to keep a complete historical database - and partially from reports. Of those we have identified, six happened in the US and five in Japan. The UK and Russia have had three apiece.

5.29pm GMT: Lufthansa is scanning aircraft that return to Germany from Japan for radioactivity – but has not detected any yet.

5.33pm GMT: Does this now count as good news? Yukiya Amano, director general of the International Atomic Energy Agency (IAEA), said it was "unlikely that the accident would develop" like Chernobyl, noting differences in design and structure of the nuclear plants.

function getOmnitureAccount_826067858001(){ return "guardiangu-news,guardiangu-network"; } function getOmnitureData_826067858001() { var omniture = new Object(); omniture.prop43="Video"; omniture.prop44="Japanese tsunami survivors return to wrecked city - video:Video:1531903"; omniture.prop45="Japan tsunami and nuclear alert - live coverage:Article:1531749"; omniture.eVar43="Video"; omniture.eVar44="Japanese tsunami survivors return to wrecked city - video:Video:1531903"; omniture.eVar45="Japan tsunami and nuclear alert - live coverage:Article:1531749"; return omniture; } Link to this video

5.45pm GMT: While the official death tolls is nearly 1,900, the final tally is likely to be far higher. In Miyagi prefecture alone the police chief has said 10,000 people are estimated to have died, while Kyodo, the Japanese news agency, talks of 2,000 bodies washed up on two shorelines in the same prefecture.

The Associated Press reports:

A tide of bodies washed up along Japan's coastline Monday, overwhelming crematoriums, exhausting supplies of body bags and adding to the spiraling humanitarian, economic and nuclear crisis after the massive earthquake and tsunami.

Here's the Guardian's latest coverage:

Miyagi prefecture

• At least 785 people confirmed dead in cities including Kesennuma, Higashimatsubara and Sendai, but local authorities fear more than 10,000 people may have died in the prefecture alone.

• Around 2,000 bodies found on two shores, including those in the town of Minamisanriku and Ishinomaki City.

• Minamisanriku has a population of 17,000, but 10,000 are missing after the tsunami.

Iwate prefecture

• At least 574 people confirmed dead, including those in Ofunato and Rikuzentakata.

• The city of Rikuzentakata, with a population of 23,000 people, was "almost completely wiped out", the fire department says. No information yet on how many survived. More than 80% of the city was flooded.

• In the town of Otsuchi, out of a population of 15,000 people 12,000 are missing.

Fukushima prefecture

• About 420 people, including those in Iwaki and Minamisoma cities, are confirmed dead. Around 1,200 people are missing.

6pm GMT: The Guardian's live Q&A on the Japan nuclear crisis has concluded, with experts answering a string of questions from Guardian readers on the crisis at the damaged Fukushima nuclear reactors.

The latest batch of questions were answered by Vaughan Cole, a member of the Institution of Mechanical Engineers and former principal specialist Inspector of Mechanical Engineering Health and Safety at the Health and Safety Executive.

To cornelia23 who asked where the electricity to power the pumps sending sea water into the reactors is coming from if there's been a power outage, Vaughan Cole replied:

Without knowing details we don't know what electrical supplies there are, but if they're managing to circulate water there must be electrical supplies - like grid supplies, local electrical supplies or diesel energy supplies or battery supplies.

BuffHoon asked if there could be problems with a build-up of radioactive steam if the mechanism required to vent the core vessel was destroyed in the explosions.

We don't know exactly what the circumstances are, if the possibility of hydrogen generation in normal operation was a design basis then you would expect provisions for the hydrogen to be safely collected and dealt with. However it may be that the systems for doing this are either overwhelmed or have been made faulty by the seismic event or tsunami.

And a more personal question from boyo: "The French issued an evacuation order to their citizens in Tokyo. Would you move your family south if they were in Tokyo?" Cole responded:

No, I'd stay in Tokyo. Currently the releases being reported are of a low level and a local nature.

Footage showing the Fukushima Daiichi nuclear power station before (bottom) and after (top) a hydrogen explosion at the number three reactor of the plant, the yellow ring in the top image shows the collapsed building after the explosion

6.15pm GMT: The cooling failure in the Fukushima Daiichi number two reactor was caused by previous the explosion in the number three reactor, knocking out four of the five pumps injecting coolant in.

To avoid a third explosion in reactor number two, similar to those in one and three earlier, operator Tepco is saying it will consider opening a hole in the wall of the building that houses the reactor to release hydrogen. What that implies I don't know but will try and find out.

This news comes from a summary by the Kyodo news agency:

Fuel rods at the quake-hit Fukushima Daiichi nuclear power plant's No 2 reactor were fully exposed at one point after its cooling functions failed, the plant operator said Monday, indicating the critical situation of the reactor's core beginning to melt due to overheating.

The rods were exposed as a fire pump to pour seawater into the reactor to cool it down ran out of fuel, Tokyo Electric Power Co said. The firm had reported the loss of cooling functions as an emergency to the government.

Tepco said water levels later recovered to cover 30cm in the lower parts of the fuel rods.

The seawater injection operation started at 4:34pm [local time JST], but water levels in the No 2 reactor have since fallen sharply with only one out of five fire pumps working. The other four were feared to have been damaged by a blast that occurred in the morning at the nearby No 3 reactor.

The utility firm said a hydrogen explosion at the nearby No 3 reactor that occurred Monday morning may have caused a glitch in the cooling system of the No 2 reactor.

Similar cooling down efforts have been taken at the plant's No 1 and No 3 reactors and explosions occurred at both reactors in the process, blowing away the roofs and walls of the buildings that house the reactors.

It is feared that the No 2 reactor will follow the same path. To prevent a possible hydrogen explosion at the No 2 reactor, Tepco said it will look into opening a hole in the wall of the building that houses the reactor to release hydrogen.

The company has also begun work to depressurize the containment vessel of the No 2 reactor by releasing radioactive steam, the government's Nuclear and Industrial Safety Agency said. Such a step is necessary to prevent the vessel from sustaining damage and losing its critical containment function.

With only one fire pump working, Tepco is placing priority on injecting water into the No. 2 reactor, although both the No 1 and No 3 reactors still need coolant water injections, according to the agency.

The blast earlier in the day injured 11 people but the reactor's containment vessel was not damaged, with the government dismissing the possibility of a large amount of radioactive material being dispersed, as radiation levels did not jump after the explosion.

Tepco said seven workers at the site and four members of the Self-Defense Forces were injured. Of the 11, two were found to have been exposed to radiation and are receiving treatment.

6.30pm GMT: Nikkei reports that Moody's rating agency is to consider downgrading Tokyo Electric Power company's credit rating, in the day's least surprising news.

6.39pm GMT: Charles Williams of the UK Red Cross blogs some of the latest figures that Japan's Red Cross has compiled:

I've just got off a conference call with the Japan Red Cross, who shared with us some headline figures about the disaster and their response to it. Some of them are staggering. All figures are approximate and will no doubt change quickly, but this is a snapshot of the current situation.

The disaster

- 2,000 people confirmed dead

- 10,000 more people expected to be confirmed dead

- 2,000 people injured

- 530,000 people displaced, staying in 2,500 evacuation centres, such as schools and public halls

- 24,000 people still completely isolated and cannot be reached

- 1.2 million homes without power

- 1.4 million homes without water

- 4,700 destroyed houses

- 50,000 damaged houses

- 582 roads cut off

- 32 bridges destroyed

The Japan Red Cross has a well-defined role in Japan's emergency plans, providing first aid and emergency healthcare services, as well as distributing relief items. It is a large, well-funded organisation and is coping admirably with the extent of the disaster.

6.53pm GMT: There are fears over what is happening to the spent nuclear fuel pools sitting within Japan's damaged Fukushima nuclear plants, the Guardian's US environmental correspondent Suzanne Goldenberg reports:

Anti-nuclear campaigners are drawing attention to some important technical aspects about the explosions at the Japanese nuclear reactor. It's an especially welcome intervention given the lack of information coming from the Japanese nuclear authorities

First, they are warning about a secondary risk of explosion and radiation link from the spent fuel pools which are located just above the reactors. That means they are outside the steel casing encirclinng the reactors, but inside the containment structures that were damaged in the explosions

Robert Alvarez, a senior policy expert at the institute of Policy Studies, said satellite pictures of the Fukushima plant showed evidence of damage to the spent fuel pool. "There is clear evidence that the fuel cask cranes that haul spent fuels to and from the reactor to the pool both fell. They are gone," he said. "There appears to be copious amounts of steam pouring of the area where the pools is located."

He said there was no evidence of fire but described the situation as "worrisome".

"What we don't know is whether or not explosions or the quake or the tsuanmi or a combination of things might have damaged support structures or compromised the pool," Alvarez said.

He warned that it could take years to repair the damage to the upper decks of the reactor and to move the discharged fuel into a safer area of storage.

Second, they note that the two reactors where the explosions took place are older models and not up to the safety standards of newer designs. Both were built by General Electric in the early 1970s, and have relatively small containment domes, relying on water pressure to cool the reactor cores.

"Designs built from the 1980s onwards don't have the vulnerabilities of the Mark 1 reactor," said Arjun Makhijani, president of the Institute of Energy and Environment Research. "The newer reactors have much more sturdy containment buildings."

The Guardian will have a separate story on the specific flaws within the reactor design at Fukushima.

7.07pm GMT: New Scientist's Short Sharp Science blog has an update on the latest situation at the damaged Fukushima plants:

The situation at Japan's embattled Fukushima-Daiichi nuclear plant has grown worse. One of the plant's four reactors is now close to meltdown, and while that's bad, it's not as apocalyptic as it might sound. New Scientist asked nuclear scientists to explain what has happened, and what the risks are.

First, "there is no possibility of a nuclear explosion," explains Richard Wakeford of the University of Manchester's Dalton Research Institute. He says any such fears are "science fiction", as there is nowhere near enough radioactive uranium 235 in the reactor to create a nuclear explosion.

The real fear is that harmful radioactive material will escape from the reactor core.

Although all four reactors automatically shut down immediately after Friday's earthquake, engineers have struggled to cool down the reactor cores, because pumps that should have driven cooling water into the reactors failed. This meant that the reactors overheated, turning the water into steam.

The rest of the blog is well worth reading.

7.17pm GMT: The American Nuclear Society has an explanation of the events in Fukushima [pdf], including this discussion of the implications of a meltdown:

Is a nuclear reactor "meltdown" a catastrophic event?

Not necessarily. Nuclear reactors are built with redundant safety systems. Even if the fuel in the reactor melts, the reactor's containment systems are designed to prevent the spread of
radioactivity into the environment.

Should an event like this occur, containing the materials could actually be considered a "success" given the scale of this natural disaster that had not been considered in the original design. The nuclear power industry will learn from this event, and redesign our facilities as needed to make them safer in the future.

7.20pm GMT: The Guardian's Suzanne Goldenberg talks to representatives from the Union of Concerned Scientists about the Fukushima reactors and what to worry about:

Two key take-aways: one on the power vulnerabilities of nuclear plants, the other on the dangers of spent fuel pools.

The nuclear emergency in Japan was caused by a cascade of failures in power supply to the plant. The earthquake and tsunami knocked out the main electricity supply lines, then the back-up diesel generator, and finally ran down the emergency battery supply.

Now here is the scary thought. The Fukushima reactor had eight-hour battery reserves.

The 23 nuclear plants of the same model in the US have just four-hour battery reserves, according to UCS's Ed Lyman.

And now the (relatively) good news. Lyman notes that the spent fuel pools, which were located above the reactors, may indeed have been compromised. "They have may suffered some structural integrity damage," he said. That raises the risk of an explosion, and possible radiation leak, from the pools if technicans are unable to restore cooling systems.

But Lyman added: "The inventory of spent fuels in the pools was well below capacity. That could limit potential impact if there was a loss of coolant to the pools."

7.30pm GMT: Here is a summary of the latest news so far today:

• The combined death toll from Japan's earthquake and tsunami is likely to exceed 10,000, reports state broadcaster NHK. About 2,000 bodies have been found washed up found on two areas of Miyagi prefecture.

• A hydrogen explosion happened at the number three reactor of the Fukushima Daiichi nuclear power plant, in the early hours of Monday morning (local time). The plant's operator Tokyo Electric Power company (Tepco) said 11 people were injured.

• Tepco said nuclear fuel rods at the reactor are exposed and overheating, raising the risk of them melting. Up to 190 people are suspected of being exposed to radiation, according to officials.

• The International Atomic Energy Agency says the Fukushima crisis is unlikely to become another Chernobyl. Authorities have set up a 20km (12 mile) exclusion zone around the Fukushima Daiichi plant. Meanwhile, the US agreed to Japan's formal request for supplies and equipment to tackle the crisis.

• Almost two million households remain without power in the north of Japan, where snow is forecast later this week, while around 1.4 million households have no running water. Those with power are being affected by rolling blackouts as electricity shortages force reductions in service in some areas.

• Japan's central bank plans to inject $85bn billion into the economy to help the banking system to function as many businesses remain closed. Economists at Credit Suisse bank are calculating the effects of the disaster on the worst hit areas to cost around $171bn.

8.16pm: This is Ben Quinn in London taking over live blogging for the next few hours.

A German rescue team with dogs at Tokyo-Narita airport. Credit: EPA

8.19pm: Liz Ford and Claire Provost of the Guardian's global development website have been reporting on the international contribution to the rescue effort in Japan.

Along with the 500 rescue specialists and 30 rescue dogs (above) who have arrived in Japan from around the world, they write that financial aid is coming from a diverse range of sources:

Countries still deeply affected by natural disasters or political unrest – including Pakistan, New Zealand, Afghanistan and Bolivia – are among those offering aid and support.

China, which is engaged in a border dispute with Japan and views its neighbour with deep suspicion, is among the 17 Asian states that have pledged help, offering $4.5m (£2.8m) in aid.

The first shipment of emergency materials, including 2,000 blankets, 900 tents and 200 emergency lights, was due to be flown from Shanghai to Tokyo today. New Zealand, meanwhile, has sent a 65-strong search and rescue team.

8.24pm: Ian Sample, science correspondent at the Guardian, has a roundup of the deepening nuclear crisis at the stricken Fukushima 1 nuclear power plant, which has continued to deteriorate today.

As engineers fought to save three reactors from meltdown and a second explosion at the site tore the roof off a containment building, he sets the scene after confirmation by Japan's Nuclear and Industrial Safety Agency (Nisa) that caesium-137 and iodine-131 have been released into the atmosphere:

These are radioactive isotopes that are produced in the core and can contaminate cooling water if fuel rods get hot enough to melt the cladding that surrounds them.

The release of radioactivity has raised health concerns and wider fears of environmental contamination.

Monitoring posts to the northwest of the power station recorded radiation levels of 680 microsieverts per hour on Monday, a dose roughly equivalent to four months of natural background radiation.

An American warship, the USS Ronald Reagan, detected low levels of radiation at a distance of 100 miles from the Fukushima plant.

Radiation levels have increased in the immediate vicinity of the power station and in surrounding areas.

People caught in the evacuation zone around Fukushima were given potassium iodide pills to protect against thyroid cancer.

Radioactive iodine is easily absorbed by the thyroid, where it can cause tumours, but the pills saturate the gland with the element and make it harder for the radioactive form to be absorbed.

8.41pm: The extraordinarily grim task of coping with the sheer number of dead as a result of the earthquake and tsunami is presenting particular challenges for the authorities in stricken areas.

Hundreds of bodies have been washing ashore since last week, according to this file from reporters for the Associated Press news agency in the coastal city of Tagajo

While the official death toll rose to nearly 1,900, the discovery of the washed-up bodies and other reports of deaths suggest the true number is much higher. In Miyagi, the police chief has estimated 10,000 deaths in his province alone.

Miyagi prefecture bore the full force of Friday's tsunami, and police said 1,000 bodies were found scattered across its coast. The Kyodo news agency reported that 2,000 bodies washed up on two shorelines in Miyagi.

Most Japanese opt to cremate their dead, and with so many bodies, the government on Monday waived a rule requiring permission first from local authorities before cremation or burial to speed up funerals, said Health Ministry official Yukio Okuda.

"The current situation is so extraordinary, and it is very likely that crematoriums are running beyond capacity," said Okuda. "This is an emergency measure. We want to help quake-hit people as much as we can."

The town of Soma has only one crematorium that can handle 18 bodies a day, said an official, Katsuhiko Abe.

"We are overwhelmed and are asking other cites to help us deal with bodies," Abe told The Associated Press.

Hajime Sato, a government official in Iwate prefecture, one of the hardest hit, said deliveries of supplies were just 10 percent of what is needed.

Body bags and coffins were running so short that the government may turn to foreign funeral homes for help, he said.

8.59pm: The New York Times has some rather worrying quotes from concerned nuclear industry executives in the US who have been talking to Japanese counterparts amid faltering emergency operations to pump seawater into one of the crippled reactors at the Fukushima Daiichi Nuclear Power Station:

"They're basically in a full-scale panic" among Japanese power industry managers, said a senior nuclear industry executive.

The executive is not involved in managing the response to the reactors' difficulties but has many contacts in Japan. "They're in total disarray, they don't know what to do."

Credit: AFP/Getty Images

9.15pm: Japan's prime minister, Naoto Kan (left), has announced that the government is setting up a joint response headquarters with the operator of the stricken Fukushima nuclear reactor to better manage the crisis.

Naoto Kan also told reporters that he will personally lead operations at the headquarters, which will be located at the main office of the Tokyo Electric Power Co, according to the Associated Press news agency.

9.43pm: Despite the insistence of the Japanese government that the crisis at the Fukushima nuclear power plant is unlikely to turn into another Chernobyl, nuclear experts are beginning to throw doubt on the accuracy of official information being issued.

They claim that it follows a pattern of secrecy and cover-ups employed in other nuclear accidents, report John Vidal and Damian Carrington of the Guardian.

"It's impossible to get any radiation readings," they were told John Large, an independent nuclear engineer who has worked for the UK government and has been commissioned to report on the accident for Greenpeace International.

The Guardian has also posted a newly released diplomatic cable obtained by WikiLeaks, which records that a high profile Japanese politician told US diplomats that the Japanese government department responsible for nuclear energy – has been "covering up nuclear accidents and obscuring the true costs and problems associated with the nuclear industry".

10.01pm: Warner Brothers has said it has taken the film "Hereafter" out of Japanese theatres and postponed the release of "The Rite" there following last week's earthquake.

"In deference to the tragic unfolding events in Japan, we have pulled 'Hereafter' from the theatres and will postpone the Japanese release of 'The Rite' (which was scheduled to open this coming weekend) to a later date," Warner Brothers said in a statement.

'Hereafter,' which was directed by Clint Eastwood and stars Matt Damon (left), follows three people who are questioning death and what may or may not come after. 'The Rite,' starring Anthony Hopkins," deals with exorcism.

10.20pm: While Germany and Switzerland have both put the brakes on their nuclear sectors (read the Guardian's coverage of those developments here) the US administration has announced that it will push ahead with nuclear power as a vital part of its energy mix.

"We view nuclear energy as a very important component to the overall portfolio we're trying to build for a clean-energy future," US Deputy Energy Secretary Daniel Poneman told reporters at the White House.

He added the administration believed US nuclear plants are safe.
"We will continue to seek to build nuclear into a part of a responsible energy future," he said, adding that nuclear power was a critical component in the US energy portfolio, with 104 operating reactors providing 20 percent of the nation's electricity.

Here is some background from Reuters setting the context to those remarks:

President Barack Obama has urged expansion of nuclear power to help meet the country's energy demands, lower its dependence on fossil fuels and reduce its greenhouse gas emissions.

Last year Obama announced $8.3 billion in loan guarantees to build the first U.S. nuclear power plant in nearly three decades.

It remains to be seen whether US domestic public opinion will swing against nuclear energy as engineers fight to prevent a meltdown at a Japanese nuclear plant following Friday's huge earthquake.

The events in Japan have shaken confidence in nuclear power in some countries while others have reaffirmed their commitment to atomic energy.

Germany suspended an agreement to extend the life of its nuclear power stations and Switzerland put on hold some approvals for nuclear power plants. Taiwan's state-run Taipower said it was studying plans to cut nuclear power output.

Since the 1979 accident at the Three Mile Island nuclear plant in Pennsylvania, many Americans have harbored concerns about nuclear power's safety.

Controversy has also dogged the nuclear power industry because of its radioactive waste, which is now stored on site at reactor locations around the country.

10.48pm: The US Geological Survey has upgraded the magnitude of Friday's deadly earthquake in Japan to 9.0, not long after Japan's Meteorological Agency did the same.

Scientists in the US had originally put the Japan quake at 8.9 so the change to 9.0 means that the quake was about 1.5 times stronger than they initially thought.

The Japan quake is now the fourth largest in the world since 1900 - behind the 2004 magnitude-9.1 Sumatra quake.

11.01pm: While political partisanship has been suspended in the face of a national catastrophe, the challenge of averting a nuclear disaster and managing reconstruction could present an opportunity for Japan's unpopular prime minister to redeem himself, according to Masahiro Matsumura, Professor of International Politics at St. Andrew's University in Osaka.

In an article for the Guardian's Comment is Free site, he writes that acting decisively has proved difficult for the government of Naoto Kan, but that it may yet rise to the current challenge:

The earthquake and tsunami may in fact prolong the life of the Kan government, at least for the next few months: the cabinet had been on the verge of resigning en masse, and the prime minister was almost forced to dissolve the lower house.

Now, however, opposition parties will have to assist the Kan government in its disaster relief and reconstruction measures, with the spirit of a grand coalition.

In the oriental tradition, a natural disaster is believed to be an omen, one that signals the disqualification of a ruler by heavenly mandate.

The collective unconscious of the Japanese people is certainly aware of such an omen. To overcome this, the Kan government will have to excel in the coming crisis management, including getting the nuclear power plants under control.

Until that outcome is clear, the world cannot know what the earthquake and tsunami means.

11.09pm: An explosion has been heard at Fukushima's second reactor, Japan's Kyodo news agency has reported.

11.13pm: The latest reported explosion at Fukushima's number two reactor was heard at 6.10am JST, around two hours ago.

11.22pm: A rupture may have occurred inside the containment vessel at Fukushima's number two reactor, Japan's NHK public broadcaster is reporting.

Although details are only slowly emerging about the explosion that was heard there a short time ago, technicians have been told to evacuate the area

A nuclear expert told the broadcaster that there may have been a radioactive leak as a result of the explosion at the containment vessel, which is supposed to prevent radiation from leaking out.

The explosion appears to be related to a fault with the suppression pool at the very bottom of the containment vessel. When it is functioning normally, steam is brought down to the pool and is used to cool the reactor.

11.38pm: Officials from Tokyo Electric Power Company, which runs the Fukushima plant, are being grilled at the moment at a press conference.

Journalists are demanding to know if the latest explosion is different from the hydrogen explosions which erupted over the weekend but the officials either appear not to know the true cause of the blast, or have decided to limit the amount of information being released.

Around 50 technicians who are directly involved in the operation are remaining at the site of the explosion.

11.44pm: There is a "possibility" that damage was done to the suppression pool at the bottom of the containment vessel inside Fukushima's number two reactor, the press conference has been told by Tokyo Electric Power Company (Tepco).

A Tepco official said that 2.7 metres of the reactor's fuel rods were now exposed at the reactor, where an explosion was heard at 6.10am (JST).

The containment vessel is the last line of defence to prevent radioactive substances from being released into the air.

According to Japan's NHK public broadcaster, winds are blowing in a northerly direction at the site of the crisis, which is 220 kilometers (135 miles) north of Tokyo.

11.57pm: Japan's nuclear safety agency has said that the explosion at the Fukushima plant's second reactor was caused by hydrogen.

Japan's Jiji news agency quoted the trade ministry as saying radiation levels remained low after the blast, the third at the plant since Saturday.

12.54am: Japanese stocks fell for a fourth day as the the Tokyo Stock Exchange opened on Tuesday morning around the same time as an alert was underway over the latest explosion at one of the country's nuclear power plants.

Bloomberg reported that the value of shares in Tokyo Electric Power Co, Asia's biggest power generator, was set to plummet by as much as 14 percent after the company confirmed a third explosion at its nuclear plant in Fukushima, north of Tokyo.

Sony, the country's biggest exporter of consumer electronics, also declined 4 percent after the company said it halted production at some factories.

Toyota Motor Corporation, the world's largest carmaker, dropped 4.4 percent as President Akio Toyoda said its dealers, suppliers and partners were "directly hit and vastly affected" by last week's earthquake and its aftermath.

1.07am: Here is a summary of some of the key developments over the last 24 hours in Japan:

• A third explosion in four days rocked a crippled nuclear power plant in northeastern Japan on Tuesday morning as authorities struggled to avert a catastrophic release of radiation.
The latest explosion at the Fukushima Dai-ichi happened in the plant's Unit 2 near a suppression pool, which removes heat under a reactor vessel, according to the plant owner, Tokyo Electric Power Co.
A government minister said it was "highly likely" that the fuel rods inside the reactor might melt. Radiation levels near the site have risen.

• Tens of thousands are still unaccounted for as the official deathtoll reached 2,800, while bodies continue to be washed ashore four days after the tsunami triggered by the earthquake.
Almost two million households remain without power in the north of Japan, where snow is forecast later this week, while around 1.4 million households have no running water. Those with power are being affected by rolling blackouts as electricity shortages force reductions in service in some areas.

• The International Atomic Energy Agency says the Fukushima crisis is unlikely to become another Chernobyl. Authorities have set up a 20km (12 mile) exclusion zone around the Fukushima Daiichi plant. Meanwhile, the US agreed to Japan's formal request for supplies and equipment to tackle the crisis.

• Japanese stocks took a hammering when the Tokyo Stock Exchange opened on Tuesday and saw its benchmark Nikkei 225 decline to its lowest point since early October 2008.
Efforts to limit the financial devastation wreaked by the earthquake, tsunami and nuclear power crisis continued with Japan's central bank planning to inject $85bn billion into the economy to help the banking system to function as many businesses remain closed.
Economists at Credit Suisse bank are calculating the effects of the disaster on the worst hit areas to cost around $171bn.

1.40am: That is all for this liveblog. Please continue to follow all the latest updates with Tania Branigan and Lee Glendinning here.