That concludes our latest updates for today.
The International Atomic Energy Agency chief says he views Japan's nuclear crisis as an extremely serious accident requiring international cooperation.
IAEA chief Yukiya Amano said he plans to meet with top Japanese officials and to visit the area struck by the devastating earthquake and tsunami a week ago that knocked out power for the cooling systems at a nuclear power plant, setting off Japan's crisis.
Amano is accompanied by a four-member team of experts.
Japan's military says it does not plan further helicopter air drops of water on overheating reactors at a tsunami-ravaged nuclear plant.
Defence ministry spokesman Ippo Mayama said that further helicopter runs were not planned, following several runs the day before. He did not say why. It was unclear what effect the water drops had on the targeted reactor.
The Bank of Japan has injected an additional 3 trillion yen into the money markets, Kyodo News reports.
The central bank's emergency operation is in its fifth day, bringing the total amount of money immediately provided to 37 trillion yen.
The bank aims to help lenders in quake-hit areas raise necessary funds by curbing interest rate hikes in money markets, where banks and other financial institutions borrow short-term money from each other.
It may take weeks to cool down the reactors at the Fukushima Daiichi plant, says a US nuclear regulator.
"This is something that will take some time to work through, possibly weeks, as you eventually remove the majority of the heat from the reactors and then the spent fuel pools," US Nuclear Regulatory Commission Chairman Gregory Jaczko told a news conference at the White House.
Continued below.Related Content
Japan disaster: Latest updates
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Rescue teams in arduous conditions
Japan disaster: Latest updates
The US is boosting radiation monitoring on its west coast and Pacific territories.
The Environmental Protection Agency (EPA) sent extra monitoring units to Alaska, Hawaii and Guam to boost an existing network of 100 air surveillance sites around the country.
No increase had yet been detected, it said.
Tokyo is willing to accept US help in dealing with the country's nuclear crisis, and is discussing the matter with Washington.
Government spokesman Yukio Edano said: "We are coordinating with the US government as to what the US can provide and what people really need.''
He added: "We have repeatedly asked for specific support, and indeed, they are responding to that."
The Australian government holds concerns for 12 of its citizens who remain unaccounted for in areas of Japan devastated by the deadly earthquake and tsunami.
Foreign Minister Kevin Rudd told reporters in Canberra every effort "humanly possible" was being undertaken to reduce the number to zero.
Earlier, Mr Rudd said Australians could have been killed in the disaster.
The official number of dead and missing has topped 16,600, with 6,405 confirmed dead.
The number of people unaccounted for following the March 11 twin disasters increased to 10,259, the National Police Agency said in its latest update.
A total of 2,409 people were injured.
The toll has increased steadily in recent days, and reports suggest it could eventually be much higher.
Japan's nuclear safety agency says smoke is rising from the damaged Fukushima nuclear reactor.
Apple's iPad 2 has been selling out in stores across the US since its launch last Friday, and the device is set to become even more scarce.
Five key components of the tablet are made in Japan, reports say.
As Japan struggles to recover from the earthquake and tsunami that struck the nation and the continuing nuclear crisis, electronic parts will be in short supply because of factory shutdowns.
The iPad 2 was scheduled to go on sale in New Zealand on March 25.
Governments are taking precautions and conducting thorough inspections of Japanese food, which is popular worldwide and available at high-end stores around Asia, and specialty shops in Europe and the United States.
Hong Kong's Centre for Food Safety has conducted radiation tests on at least 34 samples of fresh vegetables, meat and fish from Japan.
The centre reports all test results were satisfactory.
UCLA professor Keisuke Iwamoto answers reader questions about the dangers of radiation in this Los Angeles Times article.
National flag carrier Philippine Airlines (PAL) says it will accept disaster relief supplies for free transport to Japan on "space-availability" basis on any of its regular flights to the calamity-battered nation.
In Canberra today, opposition frontbencher Joe Hockey said it's "hypocritical" for Australia to rule out nuclear energy while it continues to sell uranium to the world.
Japan's unfolding nuclear crisis, triggered by the massive earthquake and tsunami, has sparked international debate about the safety of nuclear energy.
Prime Minister Julia Gillard has said Australia has no need for it and won't entertain the idea.
Finance officials from the Group of Seven major industrialised countries have agreed on co-ordinated currency intervention to support Japan's economy following the devastating earthquake.
It will mark the first time the G-7 countries have jointly intervened in currency markets since the fall of 2000.
Japan's government is planning to issue more than 10 trillion yen (US$124 billion) of emergency bonds to fund costs for disaster relief in the wake of last week's devastating earthquake, the Sankei newspaper reported.
US aviation regulators and airline meteorologists are monitoring the radiation plume drifting northeast from Japan's damaged nuclear reactors to ensure it doesn't threaten commercial jet routes.
The Federal Aviation Administration (FAA) hasn't decided whether any action is needed beyond tracking the cloud, a spokeswoman, Laura Brown, told Bloomberg today in a telephone interview.
Police say 5700 people have been confirmed dead in Japan's earthquake and tsunami disaster and another 9522 reported as missing, NHK World reports.
The hardest-hit areas are the Miyagi, Iwate and Fukushima prefectures.
There have also been deaths confirmed in other regions, including seven deaths in Tokyo.
The National Geographic website has a series of zoomable satellite photos showing 'before' and 'after' in tsunami-hit areas in Japan.
Foreign Minister Kevin Rudd is concerned Australians could be among those killed in Japan's deadly earthquake and tsunami.
Fourteen Australians remain unaccounted for in the worst-hit areas of Japan, and consular officials on the ground are working to "get that number down to zero", Mr Rudd says.
Tourism in Hawaii is expecting a crippling hit in the months following the disasters in Japan.
Hawaii is the top US destination for the Japanese, hosting more than 1.2 million of them last year. Visitors from Japan poured about US$1.9 billion of visitor revenue into Hawaii in 2010.
Each day, there are 13 direct flights from Japan to Hawaii, normally bringing in anywhere from 3,000 to 5,000 tourists.
Japanese orphans would greatly benefit from visiting summer camps in the Canadian wilds after losing parents in the recent quake and tsunami, says Japan's envoy to Canada, Kaoru Ishikawa.
At a forum on international relations, the ambassador described the "human dimension" of the devastation back home, and suggested how Canada might help Japan recover.
The quake struck around 3pm local time when children were in school, he said.
Efforts yesterday to cool fuel rods at the Fukushima Daiichi unit 3 reactor were effective, although radiation levels were only down slightly after the operation, NHK World reported.
Two Chinook helicopters and two fire engines were used to spray sea water into the storage pool of the unit through the hole in the building's roof caused by an explosion at the reactor on Monday.
In a press conference this morning, TEPCO said radiation dropped by nearly 20 points to 292 microsieverts per hour.
This video on LiveLeak shows passengers from Japan passing through a radiation check at Taipei Airport.
The news reports that we're seeing out of Japan show scenes of devastation, suffering and grief. But in the southern parts of the country, as this J Post story shows, life goes on as normal, with supermarket shelves full of food, trains running on time and golf tournaments on TV.
Australians have been told to leave Tokyo due to the radiation risk from the earthquake-damaged nuclear reactors.
The Department of Foreign Affairs and Trade has upgraded its travel advice, which also sets an 80-kilometre exclusion zone around the Fukushima Nuclear Power Plant.
The travel advice cites the nuclear threat, as well as ongoing aftershocks and the damage to roads, buildings and communications, as reasons to leave the capital.
Engineers at Japan's stricken Fukushima nuclear power plant have successfully connected a power line to reactor 2, the UN's nuclear watchdog reports.
Restoring power will enable engineers to restart the pumps which send coolant over the reactor.
9.00am
Here's a short history of tsunamis in Japan.
US president Barack Obama has confirmed at his White House media conference that there is no radiation threat to any US territory.
8.35am
Japan-based retail chain Uniqlo is donating US$25 million to the Japanese Red Cross Society in support of earthquake and tsunami victims.
As explained on their Facebook page, the contribution includes $17 million in cash and $8 million in clothing.
8.27am
The first traces of radiation from the Japan nuclear disaster have been recorded on US soil.
Air travelers coming in from Japan have triggered radiation detectors at Chicago's O'Hare International Airport as they passed through customs. Only very small amounts of radiation were detected.
"We are aware of the radiation," said Chicago Aviation Department spokesman Karen Pride. "We are adding screenings and precautionary measures."
Actress Sandra Bullock has donated $1 million to the American Red Cross in order to help those in need following Japan's devastating tragedy last week, CNN reported.
Bullock contributed the same dollar amount last year to Doctors Without Borders in the wake of the earthquake that destroyed much of Haiti.
Emergency workers frantic to regain control of Japan's dangerously overheated nuclear complex turned to increasingly elaborate methods overnight (NZ time) to cool nuclear fuel rods at risk of spraying out more radiation.
They tried with police water cannons, heavy-duty firetrucks and military helicopters dropping bucket after enormous bucket of water onto the stricken system.
By nightfall, it wasn't clear if anything had worked, and the UN nuclear agency warned the situation was "very serious."
US president Barack Obama will be holding a media conference at the White House on the Japan crisis in about an hour's time.
The US Nuclear Regulatory Commission (NRC) believes there is no radiation danger to US territory from the nuclear reactor disaster in Japan.
People who live on the west coast of the United States have been getting jittery about the possibility of a cloud of radiation from Japan crossing the Pacific Ocean towards them. Many had been panic-buying iodine tablets.
"We don't see any concern for radiation levels that could be harmful here in the United States or any of the US territories," NRC Chairman Gregory Jaczko said this morning.
In the wake of the continuing tragedy in Japan as the result of the recent earthquakes and tsunami, Apple CEO Steve Jobs sent a message to company employees who work in the disaster-wracked country:
"To Our Team in Japan,
We have all been following the unfolding disaster in Japan. Our hearts go out to you and your families, as well as all of your countrymen who have been touched by this tragedy.....
Please stay safe.
Steve and the entire Executive Team"
The Pentagon has announced plans for a voluntary evacuation of US military families from Japan's Honshu island amid growing anxiety about radiation leaking from a crippled nuclear power plant.
Pentagon spokesman Colonel Dave Lapan said the order would apply to thousands of dependents of US military personnel at bases on Japan's biggest island.
Tokyo Electric Power Co. (TEPCO), which operates the quake-hit Japanese nuclear reactors, opened an official Twitter account last night, immediately drawing more than 117,000 followers.
"We sincerely apologise for causing serious worries and trouble over the accident at Fukushima No.1 Nuclear Power Plant, radiation leak, planned blackouts," TEPCO said in its profile in Japanese on the micro-blogging site.