TOKYO (Reuters) - Japan's nuclear regulator expressed growing alarm on Wednesday at increased contamination beside the seafront of the stricken Fukushima Daiichi nuclear power station and urged the plant's operators to take protective measures.
Fukushima's operator, Tokyo Electric Power Co., has acknowledged problems are mounting at the plant north of Tokyo, the site of the world's worst atomic disaster since Chernobyl in 1986.
On Tuesday, the company said radiation levels in groundwater had soared, suggesting highly toxic materials from the plant were getting closer to the Pacific more than two years after three meltdowns triggered by a massive earthquake and tsunami.
Shunichi Tanaka, head of the new Nuclear Regulation Authority, told reporters he believed contamination of the sea had been continuing since the March 2011 catastrophe.
"I think contamination of the sea is continuing to a greater or lesser extent," Tanaka said. "It was contaminated at the time of the accident, but I think it has been continuing for the last two years. Coming up with countermeasures against all possible scenarios is a top priority."
The NRA "strongly suspected" radiation was contaminating the Pacific, Kyodo news agency said in an earlier report from a weekly NRA commission meeting, citing Tanaka.
In the days after the tsunami, a plume of radiation from explosions fell over wide areas of the land and sea.
Toxic materials, such as cesium, were later found to have leaked through channels in the ground on the side of the station by the sea, prompting expressions of concern from South Korea and China.
On Wednesday, Chinese Foreign Ministry spokeswoman Hua Chunying said she was unaware of reports of contamination leaking into the Pacific.
An official at South Korea's fisheries ministry said regular tests were run on fish caught off the country's coast and any with contamination exceeding permitted levels banned from sale. Another ministry official said the direction of currents made it unlikely contamination would reach South Korean waters.
Tokyo Electric, also known as Tepco, said it was checking Tanaka's comments and could offer no immediate comment.
Tepco said on Tuesday an observation well between the damaged reactor No. 2 and the sea showed levels of radioactive caesium-134 and ceasium-137 had soared over the weekend.
Last month, Tepco found lower levels of cesium in groundwater flowing into the plant on ground some distance from the sea.
The operator has been flushing water over the melted fuel rods in three reactors to keep them cool for more than two years, but contaminated water has been building up at the rate of an Olympic-size swimming pool each week.
In April, Tepco warned it might run out of space to store the water and sought approval to channel what it called groundwater with low levels of radiation around the plant and to the sea through a "bypass."
Any revelations about contamination of the sea are certain to bolster local fishermen's resolve to oppose the plan.
(Reporting by Kentaro Hamada and Osamu Tsukimori in TOKYO, Meeyoung Cho and Jane Chung in SEOUL and Michael Martinez in BEIJING; Writing by Aaron Sheldrick in TOKYO; Editing by Ron Popeski)