BEIJING, Dec. 24 (Xinhua) -- China on Wednesday urged Japan to promptly clarify the situation following a water leakage involving radioactive substances at a nuclear reactor during decommissioning work.

Japanese media reported that on Tuesday radioactive water leaked at the Fugen nuclear reactor in Tsuruga, Fukui Prefecture, which is undergoing decommissioning. Japan's Nuclear Regulation Authority said that the water contains a "high" amount of radioactive substances and several people might have been exposed to radiation.

"China urges the Japanese side to fully learn the lessons of the Fukushima nuclear accident, fulfill its responsibility on nuclear safety, provide a timely explanation of the incident and swiftly address it, properly handle the decommissioning of nuclear power plants and treatment of radioactive waste, and voluntarily receive international oversight, so as to alleviate concerns of the international community," Chinese foreign ministry spokesperson Lin Jian said at a regular news briefing when asked to comment on the leakage.

The latest incident once again exposed serious deficiency in the operation, maintenance and safety supervision of Japan's nuclear facilities, Lin said.

He said recent months have seen a number of safety incidents involving nuclear facilities in Japan, which have raised serious concerns. These include the forgery of quality control of radiation detection devices at Fukushima Daiichi nuclear power plant and overflow of water from the spent fuel pool at the nuclear waste treatment plant in Rokushima Village, Aomori Prefecture, to name just a few.

Despite the many problems that exist with regard to the nuclear facilities, such as their dysfunction, chaotic management, ineffective supervision, the Japanese side still decided to restart the Kashiwazaki-Kariwa nuclear power plant that once experienced water overflow from the spent fuel pool, Lin said, noting that this decision is met by opposition and protests from the Japanese people.

This leakage again highlighted the need for the international community to further step up all-round oversight and monitoring over the management of the discharge of Fukushima nuclear-contaminated water and the operation of the equipment and facilities in order to protect the marine environment, the spokesperson said.