Vladislav Shapsha, governor of the Kaluga region which borders the broader Moscow region, said on the Telegram messaging app that the fire was promptly extinguished. He did not say at what facility it took place.

RIA reported that three containers with diesel fuel and one with fuel oil were consumed by the fire at the Pervyi Zavod refinery in Kaluga.

Shapsha said there were no casualties in the attack.

There was no immediate comment from Kyiv. Drone attacks on energy facilities inside Russia's territory have become more frequent in the past few months. Ukraine has said that while its attacks do not target civilians, destroying Russia's military, transport and energy infrastructure undermines Moscow's overall war efforts.