A drone attack set ablaze product storage facilities at one of the largest oil refineries in southern Russia, but emergency services extinguished the fire just over two hours later, and the plant was working normally, TASS news agency reported.

The Ilsky refinery, near the Black Sea port of Novorossiisk in the Krasnodar region, has a processing capacity of around 6.6 million tonnes per year.

"The consequences of the incident were eliminated," the news agency reported, citing the plant's press service. It said that the circumstances of the fire and damage were being assessed.

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. -Reuters