The operator of the Fukushima nuclear plant admitted that radioactive groundwater has leaked out to sea, fuelling fears of ocean contamination.
The admission yesterday came the day after Japanese voters went to the polls in an election for the upper house, handing the largely pro-nuclear party of Prime Minister Shinzo Abe a handsome majority.
Earlier this month Tokyo Electric Power (Tepco) said groundwater samples taken at the battered plant showed levels of possibly cancer-causing caesium-134 had shot up more than 110 times in a few days.
Tepco did not know the exact reasons for the increased readings but had maintained the toxic groundwater was likely contained by concrete foundations and steel sheets. "But now we believe that contaminated water has flowed out to the sea," a spokesman said.
But the spokesman insisted the impact of the radioactive water on the ocean would be limited.
"Seawater data have shown no abnormal rise in the levels of radioactivity," he said.
Tepco, which is surviving with massive public funds, said it would step up efforts to reduce underground water by consolidating soil near the harbour.
Radioactive substances released by the meltdowns of reactors in the aftermath of the huge tsunami of March 2011 have made their way into underground water, which usually flows out to sea. Environment experts warn such leakage may affect marine life and ultimately humans who eat sea creatures.
Tetsu Nozaki, chairman of Fukushima Prefectural Federation of Fisheries Co-operative Associations, voiced concern over the leakage. "It was quite shocking," he said. "Tepco's explanation is totally different from the one in the past."
Fishing around Fukushima was halted and the government banned beef, milk, mushrooms and vegetables from being produced in surrounding areas.
Tepco said earlier this year that a fish contaminated with radiation levels more than 2,500 times the legal limit had been caught at a port inside the Fukushima plant. Last week it said 2,000 people who had worked at the plant faced a heightened risk of thyroid cancer.