The refinery’s management said operations were suspended after drones struck targeted infrastructure.
The plant’s management said a drone attacked a large Russian refinery close to the Ukrainian border, sending a cloud of flames and black smoke into the sky, halting operations.
Officials at the Novoshakhtinsk refinery in Russia’s Rostov region said the first drone hit a crude distillation unit at 8.40am (0540GMT), causing an explosion and fireball.
The second attack, which occurred at 9:23 a.m., targeted a crude oil reservoir at the refinery of the largest supplier of petroleum products in southern Russia, but did not cause a fire, according to plant management. No one was reported injured.
Attacks and shelling were reported in the Russian region bordering Ukraine after Moscow sent troops into the neighbouring country on February 24 for what is still known as a “special military operation”.
The refinery is located in southwestern Russia, just 8 kilometers (5 miles) from the Ukrainian border.
“Due to terrorist operations on the western border of the Rostov region, two drones attacked technical facilities in Novosakhtinsk,” a statement from the plant said.
“Staff have been evacuated and technical equipment has been stopped to assess the damage.”
Ukrainian officials had no immediate comment on the alleged attack.
Rostov Governor Vasily Golubev said the refinery was suspended. Fragments of two drones were found at the refinery, he said.
Video posted on social media appeared to show a drone flying towards the refinery before raising a large fireball. Al Jazeera was unable to verify the authenticity of the video.
The refinery started operations in 2009 and has an annual capacity of 7.5 million tons.
Russia’s energy ministry said the fire had not affected gasoline and diesel supplies to consumers in southern Russia.
The alleged attack on the refinery on Wednesday followed a series of explosions and fires in western Russia during Moscow’s war with Ukraine.
Russia is investigating the cause of a fire in late April at an oil storage facility in the city of Bryansk, 154 kilometers (96 miles) northeast of the Ukrainian border.
Some other explosions The fires hit refineries, oil depots and ammunition storage facilities. Ukraine has not been officially responsible for the incidents. Some Ukrainian media claimed it was the result of the Ukrainian attack.