A drone allegedly targeted an oil refinery in Russia's Rostov Oblast overnight on May 4, the region's governor Vasilii Golubev wrote on his Telegram channel.
According to Golubev, the fire resulting from the explosion was "immediately extinguished" and damage to infrastructure was "insignificant."
Rostov Oblast borders eastern Ukraine's Donetsk and Luhansk Oblasts.
Since the start of Russia's all-out war against Ukraine on Feb. 24, 2022, there have been multiple reports about fires breaking out across Russia and other acts of sabotage which some believe to be carried out by the Ukrainian military or local partisan groups.
Local officials reported on May 1 that power lines were blown up in Russia's Leningrad Oblast, and a train carrying fuel supplies was derailed in Bryansk Oblast.
The head of the Russian occupation authorities in Russian-occupied Sevastopol claimed a drone attack on April 29 caused a large fire at an oil depot in the city's port.
However, Ukraine has not claimed responsibility for these incidents.