Following the explosion at a quake-hit nuclear plant in Japan, a state of emergency has been declared at a second facility due to excessive radiation levels there, the UN atomic watchdog said on Sunday.
"Japanese authorities have informed the IAEA that the first or lowest state of emergency at the Onagawa nuclear power plant has been reported by Tohoku Electric Power Company," the International Atomic Energy Agency said in a statement.
The alert was declared "as a consequence of radioactivity readings exceeding allowed levels in the area surrounding the plant. Japanese authorities are investigating the source of radiation," the watchdog said.
According to the authorites, the three reactor units at the Onagawa nuclear power plant "are under control," the IAEA added.
Regarding the ageing Fukushima plant, where an explosion occurred on Saturday, the IAEA said that venting of the reactor Unit 3 had started at 9.20am local time in Japan "through a controlled release of vapour."
The operation was intended to lower pressure inside the reactor containment, the IAEA said.
Following the failure of the high pressure injection system and other attempts of cooling the plant, the authorities had first injected water and then sea water into the unit.
"The authorities have informed the IAEA that accumulation of hydrogen is possible," the statement said.
The IAEA said it was continuing to "liaise with the Japanese authorities and is monitoring the situation as it evolves."