Russia said on Friday that it had thwarted a Ukrainian drone attack near a nuclear plant in the country’s south, where two news outlets said an explosion had damaged the facade of a warehouse storing nuclear waste. 

The defence ministry said air defences foiled “an attempt by the Kyiv regime to carry out a terrorist attack” when they intercepted a drone late on Thursday near the settlement of Kurchatov in the southern region of Kursk.

Kurchatov is the location of the Kursk nuclear power station, which said in a separate statement that an attempt to attack it with not one but three drones had been thwarted.

It said there were no casualties or damage, and that radiation levels were normal and the plant was operating as usual.

Baza and Shot, two Russian news outlets with good security sources, both said that two of the drones failed to detonate but the third exploded near the waste storage building.

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Kursk is one of several southern regions of Russia that have regularly come under drone attack in the course of the 20-month war that began with Russia’s full-scale invasion of Ukraine in February 2022. The governor of Kursk reported a previous drone attack on Kurchatov on Sept. 1.

Ukraine generally declines to confirm or deny military operations inside Russian territory.

Thursday night’s incident came a day after Ukrainian President Volodymyr Zelenskiy said a Russian drone attack in Ukraine’s western Khmelnitskyi region had probably targeted the area’s nuclear power station.

The U.N. nuclear watchdog said that attack destroyed “numerous windows” at the site but did not affect the Ukrainian plant’s operations or its connection to the electricity grid.