Radiation levels in the sea off the Fukushima Daiichi plant have soared to 1,250 times normal just over two weeks after it was battered by a huge earthquake and a tsunami, but it was not considered a threat to marine life or food safety, the Nuclear and Industrial Safety Agency said.

"Ocean currents will disperse radiation particles and so it will be very diluted by the time it gets consumed by fish and seaweed," said Hidehiko Nishiyama, a senior agency official.

The crisis at the plant, 240 km (150 miles) north of Tokyo, has overshadowed a relief and recovery effort from the magnitude 9.0 quake and the huge tsunami it triggered on March 11 that left more than 27,100 people dead or missing in northeast Japan.

Yukiya Amano, director general of the International Atomic Energy Agency (IAEA), cautioned that Japan's nuclear emergency could go on for weeks, if not months more.

Reuters