More evacuations were ordered Saturday morning after the cooling system at a second nuclear power plant broke down in the wake of the massive earthquake that hit Japan a day earlier, dpa reported.
Residents within 3 kilometres of the Fukushima Daini power plant, also known as Fukushima II, were ordered to leave their homes. Earlier Saturday, authorities extended evacuations to residents living within 10 kilometres of another nearby nuclear plant, Fukushima Daiichi, also known as Fukushima I, where the cooling system experienced troubles Friday.
Radiation measurements inside the Fukushima Daiichi nuclear plant were 1,000 times higher than normal after the massive earthquake in northern Japan, the Kyodo news agency reported early Saturday, citing Japan's nuclear safety agency.
Authorities were concerned that radioactivity may have escaped the plant due to high pressure inside an overheating reactor. The earthquake damaged power supplies and disrupted the reactor's cooling systems. An observation post near the plant's gate recorded radiation levels eight times higher than normal.
The cooling system for three reactors at Fukushima Daini were also not operating, the Kyodo news agency reported.
Prime Minister Kan Naoto toured the disaster area by helicopter.
Aftershocks on Saturday were continuing to rattle traumatized survivors.
More than 1,000 people were feared dead after Friday's 8.9- magnitude earthquake hit north-eastern Japan, generating a 10-metre- high tsunami that swept away people, cars, boats, crops and buildings.
It was the strongest tremor ever recorded in quake-prone Japan.
The quake generated tsunami alerts across the Pacific, as far away as Chile.
Japanese nuclear authorities earlier informed the Vienna-based International Atomic Energy Agency (IAEA) that they have declared a nuclear emergency situation at Fukushima Daiichi, and that a heightened alert condition was declared at the nearby Fukushima Daini nuclear power plant.
Citing Japanese official reports, the IAEA said on its website that the earthquake had cut the off-site power to the Fukushima Daiichi plant. Diesel generators meant to provide emergency power for the cooling system were disabled by flooding from the tsunami and had not yet been restored.
The Fukushima Daiichi nuclear plant, operated by the Tokyo Electric Power Co, has three reactors. Their radioactive cores need continued cooling to prevent meltdown.
Mobile power supplies were delivered to the plant to restore the cooling system, which had been operating on batteries, the industry news outlet World Nuclear News said, citing an official statement.
US Secretary of State Hillary Rodham Clinton said the US Air Force in Japan had transported coolant to the plant.
The IAEA said that its Incident and Emergency Centre was in "full response mode" and monitoring the situation in coordination with Japanese authorities.