The fault line that caused Monday's major earthquake in central Japan may extend beneath the Kashiwazaki-Kariwa nuclear power station in Niigata prefecture, Kyodo News said Wednesday.

The epicenter of the magnitude 6.8 quake was around 9 kilometers northeast of the nuclear plant and some 17 km underground. Aftershocks have been observed in a 15 km-wide, 30 km- long strip southwest of the epicenter, the report said. The fault line is believed to be descending underground from a Sea of Japan area toward the shore.

An official from the nuclear plant operator, Tokyo Electric Power Co., was quoted as saying that "after looking at aftershock location data, we have come to realize a fault lies right below the nuclear power plant."

Concerns over safety of the nuclear plant has been raised as a series of incidents occurred at the earthquake. Some 50 cases of water leakage, fire, radiation leak and other problems have been confirmed by Tuesday evening at the Kashiwazaki Kariwa nuclear power plant, the world's largest nuclear power plant complex in terms of output capacity.

The incidents included a fire, leakage of water containing radioactive material, detection of a small quantity of radiation from a ventilation filter and toppling of drums containing low- level radioactive waste, the operator Tokyo Electric Power Co. said.

It is reported that chief of the International Atomic Energy Agency Mohamed ElBaradei said Wednesday that the UN nuclear watchdog will be ready to join Japan in investigating the incidents at the Kashiwazaki-Kariwa nuclear power plant.

Chief Cabinet Secretary Yasuhisa Shiozaki told reporters Wednesday that building nuclear plant on solid rock layers should be a basic principle. He urged the operator to have the public informed about any incidents happened in the nuclear plant.

The radiation leak in water discharged into the sea from the Kashiwazaki-Kariwa nuclear power station after Monday's strong earthquake, was initially put at 60,000 Bq and later found to be 90,000 Bq, Tokyo Electric Power Co. said Wednesday, noting the underreport was due to "computation errors".

The amount of radiation still "falls below the safety standard set by the state and there is no safety problem," a company official said.

(Xinhua News Agency July 18, 2007)