A drone attack set ablaze parts of an oil products reservoir at a refinery in southern Russia, but emergency services said they extinguished the fire just over two hours later, TASS news agency reported early on Thursday.
TASS said the incident occurred at the Ilsky refinery near the Black Sea port of Novorossiysk in the Krasnodar region.
A day earlier, a fuel depot further to the west caught on fire near a bridge linking Russia's mainland with the occupied Crimea peninsula.
"A second turbulent night for our emergency services," Krasnodar governor Veniamin Kondratyev wrote on Telegram, adding that tanks with oil products were on fire at the Ilsky refinery.
There were no casualties, he said, citing preliminary reports and he did not say how the fire started.
Ukraine rarely claims responsibility for what Moscow says are frequent drone strikes against infrastructure and military targets, particularly in regions close to Russia.
Moscow blamed Ukraine for an attack on April 29 that set fire to an oil depot in Sevastopol. Kyiv's military says undermining Russia's logistics is part of preparations for a long-expected counteroffensive.