The pipeline has been at the centre of a standoff between Ukraine, the EU, and Hungary and Slovakia – which still import Russian oil via the pipeline.

Kyiv hopes the resumption of supplies will unblock the last hurdle to securing tens of billions of euros in support from Brussels that has been held up by Hungary’s outgoing nationalist leader Viktor Orban.

Hours after Ukraine said oil had started flowing, EU officials gave preliminary approval for the long-stalled loan of €90 billion (US$106 billion) to be disbursed.

“Oil transit was launched and pumping began,” an energy industry source in Ukraine told AFP.

Hungary and Slovakia confirmed transit had started and said supplies should start arriving Thursday.

Hungarian energy giant MOL said it “expects the first crude oil shipments following the restart of the Ukrainian section of the pipeline system to arrive in Hungary and Slovakia by tomorrow at the latest”.

Slovakia’s economy minister Denisa Sakova also said the first deliveries were expected in the early hours of Thursday, in a post on Facebook.

Hungary’s Orban had blocked the multibillion-euro loan for Ukraine as leverage to pressure Kyiv to resume oil deliveries, accusing it of stalling repairs.

His defeat in elections this month was seen as paving the way for the money to be unlocked.

Slovak prime minister Robert Fico, who has repeatedly clashed with Kyiv and Brussels, said today that he “would not be surprised if the 90 billion loan were unblocked and then oil supplies were cut off again”.

Ukrainian president Volodymyr Zelensky has made no secret of his opposition to the fact that some EU members still buy Russian oil and gas, a key source of revenue for Moscow to fund its invasion launched more than four years ago.