North Korea's state media slammed Japan on Wednesday over its suspected plan to discharge radioactive water into the sea, saying it would be a criminal act that could bring about a nuclear calamity in the region.

Environmentalist group Greenpeace earlier said that Japan is planning to discharge about 1 million tons of radioactive water from its crippled Fukushima nuclear power plant into the Pacific Ocean. Japan has said that it has not made any specific decision yet on how to dispose of the contaminated water.

"The islanders who forced untold unhappiness and pains upon our people in the past are now intending to cause a nuclear calamity with radioactive water," the Rodong Sinmun, the North's official newspaper, said apparently referring to Japan's 1910-45 colonial rule of the Korean Peninsula.

"We will never tolerate contamination of our blue sea by nuclear waste," the paper said. "(Japan) should heed a grave warning from the international community, stop taking reckless action and pull out of its plan to discharge contaminated water."

The North's Korean Central News Agency (KCNA) also carried a similar article Wednesday, accusing Japan of its suspected plan to dispose of radioactive water.

"It is an outright challenge to an international convention and presents a grave threat to survival and safety of humankind," the KCNA said, referring to the Basel Convention, a multinational agreement that restricts transboundary movement and disposal of hazardous wastes.

North Korea has recently stepped up its pressure on Japan to drop any plan to discharge radioactive water, saying the Korean people would bear the brunt of its consequence.

South Korea has also repeatedly said that the contaminated water issue should be handled in a way that does not affect the health of the citizens in the region and the marine environment in the vicinity of the nuclear plant. (Yonhap)