A fire broke out at a Russian nuclear power plant on Sunday after the country's military shot down a Ukrainian drone, the facility said after the fire was extinguished.

"An unmanned aerial vehicle (UAV) of the Ukrainian Armed Forces was shot down by air defense systems near the Kursk Nuclear Power Plant," the plant's press service said in a statement on the Telegram messenger app.

"The drone exploded on impact, causing damage to the auxiliary transformer."

The press service added that there were no casualties, but the detonation reduced the power output of the station's third power unit to 50%. The destroyed drone also caused a fire, which has now been extinguished, the press service clarified.

"The radiation background at the Kursk Nuclear Power Plant site and the surrounding area has not changed and is consistent with the natural background," the press service reported.

The International Atomic Energy Agency has repeatedly warned of the danger of fighting near nuclear power plants since Russia launched a military offensive in Ukraine in February 2022.

The plant is located near the Russian-Ukrainian border, west of the city of Kursk, a regional center with a population of about 440,000 people.

There has been no comment from Ukraine so far. Kyiv stated that its strikes on Russian territory are a response to Russia's ongoing attacks on Ukraine and are aimed at destroying infrastructure deemed critical to Moscow's overall military effort.

This attack appears to be part of a nightly wave of Ukrainian drone attacks, some targeting Russian energy infrastructure. Russia has been persistently attacking Ukraine's energy grid since its full-scale invasion in 2022.

About 10 Ukrainian drones were shot down over the port of Ust-Luga in the Leningrad region of northern Russia, and their debris sparked a fire at Novatek's massive fuel export terminal and processing facility in the Baltic Sea, the region's governor said.

"Firefighters and emergency services are currently working to extinguish the fire," Alexander Drozdenko, governor of the Leningrad Region, where the Ust-Luga port is located, reported on Telegram. He added that there were no injuries.

According to Novatek, the Ust-Luga complex, opened in 2013, processes gas condensate into light and heavy naphtha, jet fuel, fuel oil, and gas oil, allowing the company to supply petroleum products and gas condensate to international markets.

The Ministry of Defense reported that overnight, Russian units destroyed a total of 95 Ukrainian drones over 13 regions, including Leningrad and Samara, as well as the Crimean Peninsula, which was annexed by Russia.