Zelensky said a confinement structure at the plant was cut off from power for more than three hours after a Russian strike on an energy substation in Slavutych, a village built for personnel evacuated after the 1986 disaster.

"Everything functions normally today," Ukraine's energy ministry told AFP on Thursday.

The Chernobyl zone administration told AFP that the plant's New Safe Confinement -- a protective structure which covers both the exploded reactor unit and its original shelter to stop the release of radioactive material -- was "operating in usual mode."

Russia's troops seized control of the site in northern Ukraine on the first day of their February 2022 invasion.

Ukraine's nuclear sites have suffered repeated Russian attacks throughout the war, raising fears about a possible nuclear disaster.

The 1986 explosion of reactor number four was the world's worst nuclear accident, exposing hundreds of thousands of people to elevated levels of radiation.