Ukraine began nuclear disaster response drills on Thursday in the vicinity of the Russian-occupied Zaporizhzhia nuclear power station in the south of the country, regional officials said.

Kyiv accused Russia this month of planning a "terrorist" attack at the plant involving the release of radiation. Moscow denied the accusation. Yuriy Malashko, the governor of the Zaporizhzhia region which includes the plant, said the drills had begun in the city of Zaporizhzhia and the district around it.

Similar exercises started in the neighbouring Kherson region, Kherson region governor Oleksander Prokudin said.

"The purpose of the event is to coordinate the actions of all services in case of a real threat of an emergency situation at the Zaporizhzhia Nuclear Power Plant," he said on the Telegram messaging app, urging residents to remain calm.

Prokudin said various officials and civil defence forces were working jointly on scenarios that might follow a nuclear disaster, and on how to inform and evacuate the population. Authorities were testing alert systems.

The Zaporizhzhia nuclear power plant, Europe's largest, is located near the city of Enerhodar in southern Ukraine. The plant has been occupied by Russia since early March last year, shortly after Moscow's full-scale invasion.

President Volodymyr Zelenskiy urged the international community this month to put pressure on Russia to end its occupation of the plant and guarantee nuclear safety.

Kyiv and Moscow have accused each other of shelling the vast complex. Both sides have described this as "nuclear terrorism."

Ukraine, then part of the Soviet Union, suffered the world's worst nuclear accident in 1986, when clouds of radioactive material spread across much of Europe after an explosion and fire at the Chornobyl nuclear power plant.