Russia's evacuation of a town by the Zaporizhzhia nuclear power plant has led to "mad panic" with five-hour traffic queues to leave, said the Ukrainian mayor of Melitopol. Ivan Fedorov shared a photo of stationary traffic he claimed were vehicles that were trying to leave the area.

In a Telegram post he claimed that the Russians had sparked a "mad panic and no less mad queues." He said that the photo "didn't need words" and was taken by a checkpoint on a road from Melitopol to Crimea.

Russian forces have been evacuating residents from the town that serves the Russian-occupied Zaporizhzhia nuclear power plant in southern Ukraine, the Ukrainanian military said on Sunday. Ukraine is expected to begin a much-anticipated counteroffensive to retake Moscow-held territory, including in the Zaporizhzhia region.

In its morning update, Ukraine's General staff said Russian forces were evacuating local Russian passport-holders to the port city of Berdyansk and the town Prymorsk, both on the coast of the Sea of Azov.

"The first to be evacuated are those who accepted Russian citizenship in the first months of the occupation," it said in a statement.

The head of the UN's nuclear power watchdog warned on Saturday that the situation around the station, Europe's largest, has become "potentially dangerous". Both sides have accused one another of shelling the plant and efforts to secure a safety zone around it have failed.

Rafael Grossi, director general of the International Atomic Energy Agency (IAEA), called for measures to ensure the safe operation of Europe's largest nuclear plant as evacuations were under way in the nearby town of Enerhodar.

"The general situation in the area near the Zaporizhzhia nuclear power plant is becoming increasingly unpredictable and potentially dangerous," Grossi said on the agency's website. "I'm extremely concerned about the very real nuclear safety and security risks facing the plant. We must act now to prevent the threat of a severe nuclear accident and its associated consequences for the population and the environment." Grossi said that while the operating staff of the plant remain at the site, the conditions for the personnel and their families are "increasingly tense."