The Nuclear Regulation Authority has sacked a senior official in its secretariat for leaking information to a nuclear power plant operator that could undermine the new watchdog's obligation to act in a transparent and neutral manner, its officials said.

The NRA said the official, Tetsuo Nayuki, 54, on Jan. 22 handed Japan Atomic Power Co. a draft assessment report on geologic faults running beneath its Tsuruga nuclear plant in Fukui Prefecture — just about a week before it was due to be made public by a panel appointed by the regulator.

"It is extremely regrettable that a senior official did such a thing. It was a thoughtless act, because we should be especially careful when having contact with parties subject to regulations and should be transparent in the exchanges," NRA Chairman Shunichi Tanaka was quoted as saying by the nuclear watchdog's spokesman, Hideka Morimoto.