The operator of Japan's tsunami-crippled Fukushima Daiichi nuclear station said on Wednesday that it has sealed a fresh leak of radioactive water at the plant that it suspected was seeping into the ocean.

A spokesman for Tokyo Electric Power said workers stopped a leak discovered earlier in the day into a storage pit outside Daiichi's No.3 reactor and within meters of the ocean.

The plant's No.2 reactor developed similar leaks which the operator managed to seal last month with liquid glass and other substances.

Since the devastating March 11 earthquake and tsunami in northeastern Japan disabled the plant's cooling systems, Tokyo Electric has poured water on the reactors to forestall disastrous meltdowns.

The utility has scrambled to find means of storing the contaminated water, some of which has seeped into the ocean.

Japan's foreign ministry has notified the United States and neighboring countries of Wednesday's leak, said Hidehiko Nishiyama, a spokesman for the country's nuclear safety watchdog.

China and South Korea harshly criticized Japan when it began dumping thousands of tonnes of contaminated water into the sea from the plant last month with little prior notice.

(Reporting by Shinichi Saoshiro; Editing by Edmund Klamann)

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