The alleged incident joins a string of recent drone attacks announced by Russia, including what it said was an attempt to assassinate President Vladimir Putin on Wednesday.

The fire at the oil refinery’s reservoir, in the southern Krasnodar region’s Ilsky settlement, started after an attack by “an unidentified drone”, an emergency services official told TASS.

Krasnodar Governor Veniamin Kondratyev said the refinery fire had been localised to a 400-square-metre (4,300-square-foot) area and was quickly extinguished by emergency services.

In the nearby village Volna, a similar blaze at an oil reservoir engulfed 1,200 square metres, with officials blaming a drone crash.

That same day, Moscow said it shot down two drones aimed at Putin’s residence and accused Ukraine of attempting a “terrorist act”.

Kyiv insisted it had “nothing to do” with the alleged drone attack, suggesting instead it was “staged” by Moscow, while the United States expressed scepticism about any allegations made by Russia.

The spate of apparent sabotage attacks has been used to underscore Russia’s exposure to enemy blows as the Kremlin gears up for important anniversary celebrations.

The May 9 victory lap that commemorates the Soviet defeat of Nazi Germany in World War II has become a central event during Putin’s rule.