Russia said on Monday it would investigate the cause of a large fire that erupted in the early hours of the morning at an oil storage facility in the city of Bryansk 154 km (96 miles) northeast of the border with Ukraine.
Unverified social media footage showed what sounded like two explosions followed by a tower of flames, with one unverified video showing a fire raging around a giant fuel reservoir.
Russia's Ministry of Emergency Situations said nobody had been hurt in the incident.
The ministry said in a statement that the fire had broken out at a facility owned by oil pipeline company Transneft at 0200 Moscow time (2300 GMT), and that there had been no need to evacuate any parts of Bryansk, a city of 400,000 people.
The energy minister declined immediate comment.
Other unverified footage showed what looked like another fire burning at a second location in Bryansk.
There was no immediate indication that the fire or fires were related to Ukraine, which has mounted fierce resistance against Russia since President Vladimir Putin sent troops into Ukraine on Feb. 24 in what he called a special operation.
There was however unconfirmed speculation on social media that the fire or fires were the result of a Ukrainian missile strike.
There was no immediate comment from Ukraine which has denied or not responded to previous suggestions that it has struck targets inside Russia.
Russian officials said last week that Ukrainian helicopters had hit residential buildings and injured seven people in the Bryansk region. Ukraine's defense ministry did not respond to a request for comment on that allegation at the time.