Ukrainian forces staged an overnight drone attack that set several oil storage tanks ablaze near the town of Azov in southern Russia, a source in Kyiv told AFP on Tuesday.
Kyiv has carried out several similar attacks on Russian energy facilities in recent months, arguing they are fair targets given that they fuel Moscow's military.
Russia has also launched dozens of devastating attacks on Ukrainian power plants throughout its two-year invasion, crippling the country's energy grid.
"Oil product tanks caught fire in Azov as a result of a drone attack. According to preliminary data, there were no casualties," the governor of the local Rostov region, Vasily Golubev, said.
Video published by Russia's emergencies ministry showed thick smoke and flames billowing out of what appeared to be multiple oil storage tanks in an undisclosed location.
Ukraine did not say how many drones were involved in the attack.
"The (Security Service of Ukraine) SBU will continue to impose 'drone sanctions' on Russia's oil refining complex and reduce the enemy's economic potential, which provides the aggressor with resources to wage war against Ukraine," the defence-linked source said.
It also claimed that SBU drones have carried out more than 20 successful attacks on Russian oil facilities in various regions.
Some 200 firefighters and emergency personnel were deployed to deal with the blaze, which spanned an area of at least 3,200 square metres (3,800 square yards), Russia's emergencies ministry said.
The Rostov region sits directly across the border from Ukraine and is home to the operational headquarters overseeing Russia's invasion.
On the battlefield, Ukraine said Russian forces were fighting to enter the outskirts of Chasiv Yar, a flashpoint town in the east whose capture could accelerate Russian advances.
Ukraine's eastern region of Donetsk, where war-scarred Chasiv Yar lies, has borne the brunt of fighting over more than two years and the Kremlin claims the region is part of Russia.
"The enemy keeps trying to advance to the micro-district Novy in the town of Chasiv Yar," Ukraine's military said in a briefing.
Further south, it said Moscow's forces were also pushing towards Pokrovsk, where they were closing in on a key road that would complicate supplies between strategic hubs in the region.
A 24-year-old Ukrainian serviceman, who identified himself with his call-sign Dykyi, dismissed concerns Russians could render the road impassable for Ukraine.
A colleague, who did not give his name, however noted that Russian forces were already flying drones and launching missile attacks at the road.
"It will definitely not be blocked for the military," Dykyi told AFP at a training ground in the Donetsk region, over the sounds of gunfire.
He said that even if Russian forces do advance towards the thoroughfare, military engineers could craft new routes or fix alternative roads in bad repair.
"As long as the weather is good, there are routes everywhere," he said.
Ukraine's air force meanwhile said it had downed 10 Iranian-designed attack drones launched by Russian forces overnight.
