Drones operated by Ukraine's military intelligence agency (HUR) attacked military targets in Russia's Volgograd, Lipetsk and Kaluga oblasts overnight on May 12, Ukrainska Pravda reported, citing its unnamed source in HUR.
One target was an oil refinery in Volgograd, where a fire was reported by local Russian authorities, according to the media outlet.
The Kaluganefteprodukt oil depot and the Novolipetsk metallurgical plant were also reportedly struck by drones.
"These military targets were hit by Ukrainian-made drones. The work will be continued," the source told Ukrainska Pravda.
The Kyiv Independent could not verify these claims.
In recent months, drone attacks targeting energy facilities within Russia's borders have increased in frequency.
Ukraine's military intelligence agency (HUR) confirmed on May 10 it was behind the attack on the oil refinery in Kaluga Oblast.
The day before, the Security Service of Ukraine (SBU) attacked an oil refinery, Gazprom Neftekhim Salavat, in the Republic of Bashkortostan, and two oil depots in Krasnodar Krai, according to the Kyiv Independent's source.
Strikes against Russian energy targets have prompted criticism from U.S. officials, who have made it clear that Washington does not support Ukraine's attacks on oil refineries, citing fears that it could threaten the global energy market.
In response, President Volodymyr Zelensky said that Kyiv has the right to use its own weapons with retaliatory strikes on Russian oil refineries.