Officials at the Emergency Situations Ministry said a fall in water levels at a steam generator in the third reactor of the Rivne nuclear power plant caused Thursday's shutdown.

The ministry said that radiation levels remained normal at the station. Officials declined to give more details.

Ukraine was the site of the 1986 Chernobyl accident, the world's worst civilian nuclear disaster.

The Rivne nuclear plant is of a different design that the Chernobyl reactor.