Radioactive groundwater at the Fukushima nuclear plant has probably risen above an underground barrier meant to contain it.
The revelation presents an "emergency" that the plant's operator is not sufficiently addressing, a regulatory watchdog official said today.
This contaminated groundwater is likely to be seeping into the sea and exceeding legal limits of radioactive discharge. A workaround planned by Tokyo Electric Power Co (Tepco) will only forestall the growing problem temporarily, Shinji Kinjo, head of a Nuclear Regulatory Authority task force said.
"Right now we have a state of emergency," Kinjo said, adding that there is a "rather high possibility" that the radioactive wastewater has breached the barrier and is rising towards the ground's surface.
A Tepco official said the utility was taking various measures to prevent contaminated water from leaking into the bay near the plant. It was not immediately clear how much of a threat the possible increase in contaminated groundwater could cause.
In the weeks following the 2011 disaster that destroyed the plant, the Japanese government allowed Tepco to dump tens of thousands of tonnes of contaminated water into the nearby Pacific Ocean in an emergency move.
The toxic water release was heavily criticised by neighbouring countries as well as local fishermen and the utility has since promised it would not dump irradiated water without the consent of local townships.