Japanese nuclear crisis escalates

Japan's nuclear crisis escalated to its worst level in two years on Wednesday, with its nuclear watchdog saying it feared more tanks were leaking contaminated water, while China expressed its shock over the disaster.

Japan's nuclear regulator also said it feared the disaster exceeded the ability of Tokyo Electric Power Co to cope "in some respects".

A spokesman for the Nuclear Regulation Authority said earlier on Wednesday that the agency plans to upgrade the severity of the crisis from a level 1 "anomaly" to a level three "serious incident" on an international scale for radiological releases.

Such a move would be the most serious action taken since the plant was destroyed by an earthquake and tsunami in 2011.

At its height, the Fukushima crisis was classified as level seven - one of only two events ever rated in that category along with the Chernobyl disaster a quarter of a century ago.

Other incidents that have been ranked level three include the 2005 radioactive waste leak at the British nuclear reprocessing facility in Sellafield.

The Japanese regulator will now inform the International Atomic Energy Agency about the leak and consult with the UN body over the accuracy of its assessment, officials said.

"Any way you look at it, this is deplorable," Chief Cabinet Secretary Yoshihide Suga said at a regular news conference on Wednesday. "The government will make every effort to halt the leak of contaminated water as soon as possible."

The plant operator, also known as TEPCO, said on Tuesday that contaminated water with dangerously high levels of radiation is leaking from a storage tank.

The NRA said it was worried about leakage from other tanks of the same type, which were built hastily to store water washed over melted reactors at the station to keep them cool.

China said it was "shocked" to hear that Fukushima was still leaking contaminated water two years after the disaster and urged Japan to provide information "in a timely, thorough and relevant manner".

"We hope that Japan will earnestly take effective steps to put an end to the negative impact of the after-effects of the Fukushima nuclear accident," China's Foreign Ministry said in a statement faxed to Reuters in Beijing.

The water in the latest leak is so contaminated that a person standing close to it for an hour would receive five times the annual recommended limit for nuclear workers in a year.

TEPCO has been criticized for its failure to prepare for the disaster and accused of covering up the extent of the problems at the plant.