The "device detonated" upon impact at the Kursk Nuclear Power Plant in western Russia, sparking a blaze which the facility said "was extinguished by fire crews".

There were no casualties from the drone smashing down at the site, where capacity was reduced.

"The radiation background at the industrial site of the Kursk NPP and the surrounding area has not changed and corresponds to natural levels," the plant wrote on Telegram.

The International Atomic Energy Agency has repeatedly warned of the dangers of fighting around nuclear plants following Russia launching its military offensive on Ukraine in February 2022.

The plant is near the Russia-Ukraine border and sits to the west of Kursk city, the region's capital with a population of around 440,000.

Russia now controls around a fifth of Ukraine, including the Crimean peninsula which it annexed in 2014.

The fighting has killed tens of thousands, forced millions to flee their homes and destroyed cities and villages across the east and south of Ukraine.

Russian President Vladimir Putin has repeatedly rebuffed calls by Kyiv and the West for an unconditional and immediate ceasefire.