Ukrainian drones on Monday hit a fuel and energy facility in the Russian region of Kaluga, a source in Ukrainian military intelligence said, the latest cross-border attack on energy facilities.
The claim came as authorities in Kharkiv -- Ukraine's second largest city -- said 19 people were wounded by a Russian missile strike on the centre of the town near Russia's border.
Moscow and Kyiv have been intensifying cross border drone and missile attacks and Russia last week launched its new Oreshnik missile on Ukraine, spurring calls for de-escalation.
"As a result of an operation by the Defence Intelligence of Ukraine, a fuel and energy facility in the Kaluga region of Russia was hit overnight," the source said.
The Russian governor of Kaluga, which lies just south of the capital Moscow, said air defence systems in the region had downed eight drones and confirmed that an "industrial enterprise" had caught fire.
Unverified images on social media of the alleged attack showed tracer ammunition cutting through the night sky and a large blaze next to two industrial chimneys.
"The target of the attack was an oil depot of Kaluganefteprodukt JSC, which is involved in supporting Russia's armed aggression against Ukraine," the source said.
Russian President Vladimir Putin said last week's strike on the city of Dnipro had tested in combat conditions "one of the newest Russian mid-range missile systems" and pledged further such "tests" would be carried out.
