Japan has held a minute's silence to mark exactly one week since the country was hit by a devastating earthquake and tsunami.
It comes as the crisis at the Fukushima 1 nuclear plant continues with emergency crews attempting to reconnect electricity to its cooling systems as four reactors continue to overheat.
Four of the facility's six reactor units have seen fires,explosions or partial meltdowns in the week since the country was hit by a massive earthquake and subsequent tsunami.
Engineers have been trying for days to avert a potentially catastrophic release of radiation from the plant but the experts in the US have said it could take weeks to cool the fuel rods down.
Officials from Tokyo Electric Power Co (Tepco) hope to fix a power cable to at least two of the reactors in the hope of restarting water pumps but have said no more seawater will be dropped on them from the air.
Smoke is still billowing out of reactor 2 but its cause is not known.
A spokesman for the Fukushima 1 plant, 150 miles (240km) north of Tokyo, has admitted the situation is "severe".
The country's nuclear agency spokesman has also conceded a "Chernobyl solution" of burying the reactors in sand and concrete was in the back of authorities' minds.
Millions of people in the north and in the capital remain indoors as fears grow of a blast of radioactive material from the complex.
The head of the UN atomic watchdog has urged Japanese Prime Minister Naoto Kan to provide more specific information on the nuclear reactors.
"We have been receiving information but there is the opinion in the international community that more detailed information is needed," said Yukiya Amano from the International Atomic Energy Agency.
The crisis has triggered alarm and reviews of safety at atomic power plants around the globe.
Even if the engineers manage to connect the power, it is not clear if the pumps will work as they may have been damaged in the quake or subsequent explosions and there are real fears of the electricity shorting and causing another explosion.
Satellite image of the nuclear plant in Fukushima pic: DigitalGlobe ISIS
Nuclear agency spokesman Hidehiko Nishiyama said it was unclear how effective spraying water on the reactors from helicopters had been, but the priority now was to get water into the spent-fuel pools.
Chief cabinet secretary Yukio Edano said: "We are co-ordinating with the US government as to what the US can provide and what people really need."
The US embassy in Tokyo has urged citizens living within 50 miles (80km) of the plant to evacuate or remain indoors "as a precaution", while Britain's Foreign Office urged citizens "to consider leaving the area".
Holly Williams: People Seeking Escape Route
Other nations have urged nationals in Japan to leave the country or head south.
Japan's Government has told everyone living within 12 miles (20km) of the plant to evacuate, and advised people within 18 miles (30km) to stay indoors.
Meanwhile, Japanese police say the number of dead or missing from last week's disaster has reached 16,600, with 6,539 killed.
And finance officials from the G7 major industrialised countries have agreed on a co-ordinated effort to weaken the Japanese yen, which has surged to record levels this week.
A super-strong yen could cripple Japanese exports and further worsen the economic impact of the crisis.