The head of Ukraine's state-run nuclear operator says Russian troops are showing signs of retreat from the Zaporizhzhia nuclear power plant in the country's south.

Energoatom President Petro Kotin said on Sunday there have been reports in the past few weeks that Russians are preparing to withdraw from the plant. He made the comment during an interview with a state-run TV station.

But on Monday, authorities in the city of Enerhodar, where the Zaporizhzhia plant is located, wrote on social media that the report of a retreat is false. They say the power station is under Russian control.

The Institute for the Study of War said on Sunday that an imminent counteroffensive by Ukrainian forces had not been confirmed in the region of Zaporizhzhia. But the US think tank quoted a military expert in Russia as saying that Ukrainian forces are preparing to retake the Zaporizhzhia plant.

The institute says it is possible Russia has started to use intelligence operations to lay the groundwork for a retreat from the plant.

Russian forces have been occupying the plant. Shelling of the site has continued.

The International Atomic Energy Agency has expressed concerns over Ukraine's nuclear facilities following last Wednesday's loss of external power at all the country's nuclear plants.

Russian forces are believed to be building defensive positions in areas on the eastern bank of the Dnipro River in southern Ukraine. This is to handle further Ukrainian counteroffensives after Russia retreated this month from the key city of Kherson.

The British Defence Ministry said in its intelligence update on Monday that Russia is firing toward Kherson from areas on the eastern bank of the Dnipro River.

The ministry also says 10 people died on the Ukrainian side on Thursday alone and that a recent high of 54 shelling incidents were reported in the area on Sunday.