Ukrainian drones have struck a major oil refinery in Russia’s Volgograd region for the second time in nearly three months, according to Ukraine’s general staff.

Pokrovsk, a railroad hub in the Donetsk region, has been turned largely into rubble, its prewar population of 60,000 now reduced to fewer than 1,300 residents.

Ukraine's military reportedly struck and damaged Russia's Volgograd oil refinery overnight on Nov. 6, Russian Telegram media channels reported, as explosions rocked several Russian energy sites.

The drone incursions and the instability on NATO’s eastern flank stem from Russia’s war in Ukraine, now approaching the end of its fourth year. The conflict has become a crucible for drone development, transforming the battlefield into a testing zone for new technology which now has applications elsewhere in Europe.

Russian Foreign Minister Sergei Lavrov accused Ukraine on Wednesday of fomenting trouble in neighbouring Belarus, and said Moscow saw no point in engaging with a Belarusian opposition council that has emerged amid nationwide anti-government protests.

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.

Ukraine's President Volodymyr Zelenskyy has signed fresh sanctions against Russia that are aligned with the European Union's 19th package and imposed new restrictions on Russian companies operating in the Arctic.

Russians carried out another drone attack on the Chernihiv region. During the day from November 5 to 6, 104 explosions were heard in the region, according to Viacheslav Chaus, head of the Chernihiv regional military administration.