VIENNA (Reuters) - Japan has told the U.N. nuclear wathchdog that a heightened state of alert has been declared at the Fukushima Daiichi nuclear power plant after Friday's major earthquake, the Vienna-based agency said.
The International Atomic Energy Agency (IAEA) said it had also been informed that the plant north of Tokyo had been shut down and that no release of radiation had been detected.
Japanese media reported separately that a leak was possible at the plant north of Tokyo as water levels fall, and that some 2,000 residents had been told to evacuate the area.
The government earlier said a cooling function at Tokyo Electric Power's (TEPCO) Fukushima Daiichi nuclear plant was not working, but there was no radioactive leakage.
The IAEA said in a statement that nuclear fuel requires continued cooling even after a plant is shut down.
"The IAEA is seeking further details on the situation at Fukushima Daiichi and other nuclear power plants and research reactors, including information on off-site and on-site electrical power supplies, cooling systems and the condition of the reactor buildings," the U.N. body said.
In Tokyo, Japan's Chief Cabinet Secretary Yukio Edano said residents that live within a 3 km radius of Fukushima Daiichi have been told to evacuate.
TEPCO confirmed that water levels inside the reactors at its Fukushima-Daiichi nuclear plant were on a falling trend, but added it was working to maintain water levels to avert the exposure of nuclear fuel rods.
The company has been trying to restore power to its emergency power system so that it can add water to the inside of the reactors, a TEPCO spokesman said.
The IAEA said it had received information from its International Seismic Safety Center that a second earthquake of magnitude 6.5 had struck Japan near the coast of Honshu, near the country's Tokai plant, but gave no details.
Japanese authorities also reported a fire at the Onagawa nuclear power plant, which has since been extinguished, the IAEA statement said.
"They say Oganawa, Fukushima-Daini and Tokai nuclear power plants were also shut down automatically, and no radiation release has been detected," the statement said.
"The World Meteorological Organization has informed the IAEA that prevailing winds are blowing eastwards, away from the Japanese coast," it said.
(Reporting by Fredrik Dahl and Michael Shields)