A seawater sample taken near the power plant on Monday showed radioactive iodine-131 concentration of about 200,000 Becquerel per cubic centimeter.

The Tokyo Electric Power Co. said this on Tuesday, clarifying that this is 5 million times the legal limit.

Right after a crack was discovered in a pit near the No. 2 reactor on April 2, radioactive materials of 300,000 Becquerel more than 7.5 million times the legal limit was detected in the nearby seawater.

A professor at Tokyo University said that it has become very clear that radiation-contaminated water is flowing into the sea.

To tackle the situation, the company tried to stop the flow of contaminated water into the sea but failed, according to VOA.

The Japanese government admitted that it would take several months to do so.

The director-general of the International Atomic Energy Agency expressed his view that the situation at the power plant "still remains very serious."

Foreign media said that the detection of radiation-contaminated fishes in the sea 85km away from the power plant sparked anxiety and uneasiness that all the seas around Japan might be contaminated with radiation.

It is expected that while radioactive materials are still spreading to other parts of the world, they will directly affect the Korean Peninsula.

MBC of south Korea predicted that radioactive materials that had leaked from the power plant would move to the sky above the peninsula by the eastward wind on Thursday.

It said there was high possibility that radioactive rain might fall on the peninsula on Thursday, adding that it would be better to avoid direct exposure to rain though it might contain low-level of radiation.

It reported that radioactive iodine was detected at 12 observatories in south Korea for 4 consecutive days from Saturday and the amounts of radioactive materials detected in Chunchon and Seoul showed a 5-fold and 2.5-fold increase respectively over those observed a week earlier.

The National Police Agency of Japan announced that the death toll caused by the quake and ensuing tsunami increased to 12,259 and the number of those unaccounted for to 15,315 as of 9 p.m. on Monday.