Ukrainian intelligence sources told Reuters on Sunday that the oil plants were hit with drone attacks.
Ukrainian President, Volodymyr Zelenskiy, thanked his military and intelligence for new “long-range capabilities” in his nightly video address.
Russia’s defence ministry wrote on Telegram that the drones “were neutralised, but a fire broke out as a result of the fall of one of the devices”.
Attacks on Russian territory via drone strikes have become increasingly frequent as the war goes on.
The Russian city of Belgorord, close to the Ukrainian border, has endured the brunt of Ukrainian operations.
This was also seen last week when pro-Ukraine groups launched ground offensives on Russian villages in the region, with one group claiming control over a town near Belgorod.
The fighting has also coincided with Russian elections as Vladimir Putin declares victory in a vote where some prominent opposition figures were barred from running.
Putin declared victory on Sunday with 87.8 percent of the vote.
He later warned NATO against any move that would risk direct conflict with Russia, saying this would be “one step away from World War 3”.
Putin said: “Everything is possible in the modern world. It is clear to everyone, that this will be one step away from a full-scale World War Three. I think hardly anyone is interested in this.”
On Ukraine, he added: “There is nothing good in this, first of all for them, because they are dying there and in large numbers.”
