Dangerous levels of radiation are leaking into the atmosphere following a fire and explosions at a nuclear plant in northeastern Japan, officials warned on Tuesday as the country reels in the wake of last week's devasting earthquake and tsunami.
Radiation levels around the Fukushima No.1 plant on the eastern coast had "risen considerably", Naoto Kan, the prime minister said, and his chief spokesman announced the level was now high enough to endanger human health.
The UN's nuclear watchdog, the International Atomic Energy Agency on Tuesday upgraded the crisis to a level-6 "serious accident" on its 1-7 scale of nuclear incidents. The Chernobyl meltdown in 1986, considered the world's worst nuclear disaster, was a grade-7 incident.
But the IAEA's Japanese chief, Yukiya Amano, moved to calm global fears that the situation could escalate further.
"Let me say that the possibility that the development of this accident into one like Chernobyl is very unlikely," he said.
In Tokyo, some 250km to the southwest, authorities also said radiation levels 10 times higher than normal had been detected in the capital, the world's biggest urban area, but said the increase didn't pose a threat to health.
Kan warned people living up to 10km beyond a 20km exclusion zone around the nuclear plant to stay indoors. Hundreds of thousands of people have already been evacuated from the affected region.
"I would like to ask the nation, although this incident is of great concern, I ask you to react very calmly," he said.
The official death toll from last week's twin disasters rose to 3,373, police said on Tuesday, while officials said at least 10,000 were likely to have perished.
Japan was shaken by more strong aftershocks on Tuesday, prompting buildings to sway in Tokyo. The first, measuring 6.2 in magnitude, struck on Tuesday night off the coast of Fukushima prefecture, 325 kilometers northeast of Tokyo. Three minutes later, a 6.0-magnitude quake rumbled under Shizuoka prefecture, 90 kilometers southwest of the capital.
"We had an aftershock of about 6-magnitude," said Wayne Hay, Al Jazeera's correspondent in Akita. "I was on the 11th story and certainly the building did sway for about 30 seconds."
Supermarkets stripped
Fearful citizens stripped supermarket shelves on Tuesday, prompting the government to warn against panic-buying, saying this could hurt the provision of relief supplies to quake-hit areas.
Scared Tokyo residents filled outbound trains and rushed to shops to stock up on food, water, face masks and emergency supplies amid heightening fears of radiation. At the city's main airports, hundreds of people lined up, many with children, boarding flights out.
Radiation levels later dropped at both the plant and in Tokyo, Yukio Edano, the chief government spokesman, said.
As well as the atomic emergency, Japan is struggling to cope with the enormity of the damage from Friday's record quake and the tsunami that raced across vast tracts of its northeast, destroying all before it.
Japan is the only country in the world to have experienced a nuclear attack - two bombs dropped by the US during World War II killed some 200,000 people - and citizens are gripped by fear of nuclear fallout.
"What we most fear is a radiation leak from the nuclear plant," Kaoru Hashimoto, 36, a housewife living in Fukushima city 80km northwest of the stricken plant, said.
"Many children are sick in this cold weather but pharmacies are closed. Emergency relief goods have not reached evacuation centres in the city. Everyone is anxious and wants to get out of town. But there is no more petrol."
More than 200,000 people have already been evacuated from the exclusion zone around the crippled plant.
