Ukraine has launched an audacious drone attack against a major Russian oil refinery as it attempts to cripple Vladimir Putin’s supply chain.

       Footage circulating online shows a huge fireball at the Afipskiy oil refinery, a crucial fuel processing plant that produces 6.25 million tons of oil annually.

       The refinery, located approximately 200km from the front line, is of vast strategic importance for the Russian war effort. It serves as a logistic hub for diesel fuel and aviation kerosene used by Russian troops.

       Andrii Kovalenko, head of Ukraine's Center for Countering Disinformation said: “Afipskiy refinery is not only an industrial facility but also an important element of Russia's military infrastructure.”

       Krasnodar Krai Governor Veniamin Kondratiev confirmed the drone attack against the region, saying that a residential complex in Krasnodar was hit.

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       According to the Russian Telegram channel Shot, residents heard “powerful explosions” at around 2 am local time with eyewitnesses also describing seeing “air defence” activity over the region's skies.

       Ukraine has regularly targeted Russian fuel sources throughout the conflict in a bid to cripple their ability to supply frontline troops. It has made good use of relatively cheap drones to do so.

       The attack comes as Russia is preparing for fresh assaults in Chasiv Yar as it continues its offensive in the Donetsk region.

       The battle for Chasiv Yar has been ongoing for months and has seen some of the conflict’s bloodiest fighting, with Ukrainian forces engaging in brutal street-to-street combat to slow down the Russian advance in the strategically important city.

       A fortnight ago, The Moscow Times reported that Chasiv Yar had fallen to Russian forces, citing five Ukrainian and European military and government sources. However, intelligence suggests that intense fighting is ongoing.

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       Lieutenant Colonel Dmytro Zaporozhets, a spokesperson for the Operational Tactical Group Luhansk, said: "Now there is a period of accumulation and concentration (of Russian forces)... on the approaches to Chasiv Yar and regrouping in the town itself for further assault operations.”

       The fighting continues whilst US President Donald Trump claims to have made progress in his bid to bring the war to a conclusion.

       Speaking aboard Air Force One, Trump told reporters he had established contact with Putin, although it is unclear whether that contact occurred before or after his inauguration.

       He said: “I've had it. Let's just say I've had it. And I expect to have many more conversations.

       "If we are talking, I don't want to tell you about the conversations. I do believe we're making progress."