A fire broke out Sunday at a Russian nuclear power plant after the country's military downed a Ukrainian drone, the facility said after the blaze was put out.

"A combat unmanned aerial vehicle (UAV) belonging to the Armed Forces of Ukraine was shot down by air defence systems near the Kursk Nuclear Power Plant," the plant's press service said in a statement on the Telegram messaging app.

"Upon impact, the drone detonated, resulting in damage to an auxiliary transformer."

The press service added that there were no injuries, but as a result of the denotation, unit three of the plant was reduced to 50 percent capacity. The destroyed drone also sparked a fire that has since been extinguished, the press service said.

"The radiation background at the industrial site of the Kursk NPP and the surrounding area has not changed and corresponds to natural levels," the press service said.

IAEA confirms normal levels

The United Nations nuclear watchdog on Sunday confirmed normal radiation levels near the plant.

"Monitoring confirms normal radiation levels near Kursk NPP," the International Atomic Energy Agency (IAEA) said in post on X.

The IAEA 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 people.

There was no immediate comment from Ukraine. Kyiv has said its strikes inside Russia are in response to Russia's continued attacks on Ukraine and are aimed at destroying infrastructure deemed crucial to Moscow's overall military efforts.

The attack appears to be part of an overnight wave of Ukrainian drone assaults partly targeting Russia's energy infrastructure. Russia has consistently targeted Ukraine's own energy grid since its full-scale invasion in 2022.

About 10 Ukrainian drones were downed over the port of Ust-Luga in Russia's northern Leningrad region, with debris sparking fire at the Novatek-operated terminal – a huge Baltic Sea fuel export terminal and processing complex, regional governor said.

"Firefighters and emergency services are currently working to extinguish the blaze," Alexander Drozdenko, governor of Russia's Leningrad region where the Ust-Luga port is located, said on the Telegram messaging app. There were no injuries, he added.

According to Novatek, the Ust-Luga complex, which opened in 2013, processes gas condensate into light and heavy naphtha, jet fuel, fuel oil and gasoil, and enables the company to ship oil products as well as gas condensate to international markets.

Russian units destroyed a total of 95 Ukrainian drones overnight over 13 regions, including Leningrad and Samara, as well as the Russian-annexed Crimean Peninsula, the defence ministry said.