Ukrainian drones struck a major oil refinery in Russia’s Volgograd region for the second time in almost three months, Ukraine said on Thursday. Russian officials did not confirm the attack, although the local governor said drones started a fire at an industrial facility.

Ukraine’s general staff said in a statement that the attack took place on Wednesday. The refinery is the largest producer of fuel and lubricants in Russia’s Southern Federal District, processing more than 15 million tons of crude annually — about 5.6 per cent of the country’s total refining capacity, according to Ukrainian officials.