Radiation levels in seawater near Japan’s stricken Fukushima nuclear plant are up to 3,355 times the legal limit.

The shock statistic adds to evidence of leaks from the reactors in the world’s worst atomic disaster since Chernobyl.

Pollution of the ocean is a concern, with fish key to the national diet. But nuclear safety officials are downplaying the risks.

“People don’t drink seawater,” said Hidehiko Nishiyama, deputy director-general of Japan’s nuclear safety agency.

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Currents would help dissipate the danger, he told a news conference.

“Furthermore, as Iodine 131 has a short half-life of eight days, even if sea produce has a high concentration of radioactive material, by the time it is consumed by humans, levels will have diminished considerably.”

Nuclear fears have largely overshadowed the humanitarian tragedy triggered by the earthquake and tsunami. But more than 175,000 people are living in shelters and with over 27,000 others dead or missing, the painful process of identifying victims continues for those who survived. Entire towns on the north-east coast have been reduced to mud and rubble.

“I don’t think we will be back on our feet any time soon but everyone has to do their part to get us back to normal,” said carpenter Yutaka Suzuki in the devastated village of Rikuzentakata.

Japan is now looking at its biggest rebuilding effort since post-World War Two reconstruction.