"There are no longer any outsiders on the territory of the Chernobyl nuclear power plant," Ukraine's state agency in charge of the Chernobyl exclusion zone said on Facebook.

Earlier in the day, the state nuclear company Energoatom said Russian troops began leaving the station and other exclusion zones, which they had occupied since the start of the Russian invasion on Feb 24.

"This morning, the invaders announced their intentions to leave the Chernobyl nuclear power plant," Energoatom said on Telegram.

Russian troops "marched in two columns towards the Ukrainian border with Belarus" and a "small number" of Russian forces remain in the station, it said.

"There is also evidence that a column of Russian soldiers who are besieging the town of Slavutych is currently being formed to move towards Belarus," it said.

Slavutych houses the workers of the Chernobyl nuclear plant.

Since the Russian invasion, there have been fears of increased radiological risks in Chernobyl.

Chernobyl's number four reactor exploded on April 26, 1986, causing the world's worst nuclear accident which killed hundreds and spread radioactive contamination west across Europe.

The site lies near the Belarus border.