AFP - A "race against time" is bound to cool reactors at the Fukushima nuclear power plant accident in Japan, said Friday the chief of the International Atomic Energy Agency (IAEA), Yukiya Amano.

"The cooling is extremely important, so I think it's a race against time," he said in Tokyo after meeting Japanese Prime Minister, Naoto Kan.

The accident at the plant "very serious", it is important that "the international community, including the IAEA," participated in efforts to secure the situation, "he said.

Mr.Amano said further that the IAEA would measure the level of radioactivity in Tokyo, probably on Friday evening, according to comments reported by the agency Jiji.

The level of injury increased by 4 to 5 on a scale of up to 7

The Nuclear Safety Agency Japanese statement Friday from April to May the level of the nuclear accident in Fukushima on the scale of nuclear and radiological events (INES), which runs until 7.

The importance of a problem occurring in a nuclear site is assessed using this scale, level 0 being no abnormality and level 7, the most important, a major accident like Chernobyl ( Ukraine) in 1986.

The increase in severity by the Japanese space agency's accident Fukushima at the same level as that at Three Mile Island (USA) in 1979.

The French Nuclear Safety Authority for its part considers that the accident Fukushima is the severity level 6.

He hopes to "help reassure the Japanese public" by making measurements distinct from those of the Japanese government.