Burgas is Bulgaria's only oil refinery, and was a key part of Lukoil's foreign business empire, which is being threatened after the US joined Britain last month in imposing sanctions on Russia's two largest oil companies over Moscow's war in Ukraine.

Russia mounted its second most-intense aerial assault overnight into Thursday, October 30, launching a salvo of 653 drones, decoys and missiles. Ukraine’s Air Force intercepted 592 drones and 31 missiles;

The US has imposed sanctions on Russia’s two largest oil companies as it called on Moscow to agree to an immediate ceasefire in its war with Ukraine.