Tokyo Electric Power Co.'s Kashiwazaki-Kariwa nuclear power plant is seen in Kashiwazaki, Japan, July 18, 2007. Officials at the world's biggest nuclear power plant said on Tuesday there had been more minor radiation leaks after an earthquake in Japan that killed nine people and forced thousands from their homes. (Xinhua/Reuters Photo)

    TOKYO, July 17 (Xinhua) -- The Kashiwazaki Kariwa nuclear power plant was under investigation by local authority Tuesday after a major earthquake led to several incidents of radioactive material leakage and fire.

    According to Jiji Press, Niigata prefectural department and officials from the ministry of internal affairs has started investigation in the nuke plant in the afternoon.

    A magnitude 6.8 earthquake rocked Niigata prefecture and nearby areas on Monday morning, causing four incidents in the power plant by now. On Tuesday afternoon, over 100 low-radioactivity waste drums were found toppled over in the plant. The lids of several containers were dislodged. Local officials said they are studying the possible effect on the environment.

    Prime Minister Shinzo Abe criticized the operator Tokyo Electric Power for being "too slow" in reporting the incidents and said it must ensure that top priority is given to the public's safety. Industry minister Akira Amari said Tuesday morning that he will instruct all nuclear plant operators in the country to reconfirm the safety of their facilities.

    Given that the epicenter of the quake was below the seabed, experts said operations at the plant will be suspended for some time as Tokyo Electric Power will need to assess how the fault line affects the facility's quake-resistance.

    According to Tokyo Electric Power Co., radioactive materials with iodine 131 and 133, chromium 51 and cobalt 60 were detected in the exhaust from the No. 6 nuclear reactor on Tuesday afternoon. The company later said that this incident would not affect surrounding environment and humans.

    On Monday, water containing radioactive material leaked from the No. 6 nuclear reactor of the nuclear power plant. The No. 6 reactor was suspended at the time for regular checks. The radioactivity level was below the legally set standard for declaring a health or environment risk, the utility company said.

    Also due to the strong quake, an electric transformer caught fire at the No. 3 reactor of the nuclear plant. The fire was brought under control around noon on Monday.

Tokyo Electric Power Co.'s Kashiwazaki-Kariwa nuclear power plant is seen in Kashiwazaki, Japan, July 18, 2007. Officials at the world's biggest nuclear power plant said on Tuesday there had been more minor radiation leaks after an earthquake in Japan that killed nine people and forced thousands from their homes. (Xinhua/Reuters Photo)