Ukrainian drones hit a Russian oil refinery in the city of Ryazan overnight, causing a fire and damaging equipment at one of Russia's biggest refineries, four industry sources told Reuters on Friday.

The reported strike comes two nights after Ukrainian forces launched a joint attack against the refinery that allegedly damaged multiple on-site facilities.

Ukraine on Sunday said that it repeatedly struck an oil refinery in Russia’s Ryazan region, the second such attack claimed by Kyiv this week. A statement by Ukraine’s General Staff claimed that the country’s armed forces, together with Ukraine’s Defense Intelligence, repeatedly struck facilities of the Ryazan Oil Refining Company.