(Reuters) - A fire that broke out in early hours of Sunday at the Afipsky oil refinery in Russia's Krasnodar region was promptly extinguished, the region's emergency security authorities said after social media reports of powerful blasts shaking the refinery.
"There were no casualties, no infrastructure was damaged, and there is no threat to the enterprise or residents of nearby settlements," the emergency administration authority of the Krasnodar region, which lies on coast of the Black Sea, said on its Telegram messaging app.
It did not provide information on what caused the fire.
Baza and Shot, two Russian news outlets with good security sources, said that the fire at the refinery, which lies 50 miles (80 km) east of the Black Sea port of Novorossiisk, one of Russia's most important oil export gateways, was caused by a drone attack.
Reuters could not independently verify the reports.
Earlier, Russia's defence ministry, without providing much detail, said that its air defence systems destroyed 36 Ukraine-launched drones over the Black Sea and the northwestern part of the Crimean Peninsula.
There was no immediate comment from Ukraine, but Kyiv has been increasingly trying to undermine Moscow's war efforts with frequent drone and saboteur attacks on Russia's military and transport infrastructure away from the frontline.
The Afipsky plant, which was last attacked in May, can process around 6 million tonnes (44 million barrels) of oil each year. The port of Novorossiisk, together with the Caspian Pipeline Consortium (CPC) terminal, bring about 1.5% of global oil to market.
The Krasnodar region is connected to Crimea - which Moscow annexed from Ukraine in 2014 - via the Crimean Bridge, itself a site of several Kyiv attacks over the course of the war that Russia launched against its neighbour 20 months ago.