Feb 23 (Reuters) - Ukrainian drones have struck a Russian pumping station serving the key Druzhba oil pipeline set up to supply Moscow's crude to eastern Europe, a Ukrainian security official said on Monday.
The overnight strike caused a fire at the station more than 1,200 km (750 miles) from the Russia-Ukraine border, added the official from Ukraine's SBU security service who did not give any details on any broader impact on the pipeline.
The attack, the latest of a string of Ukrainian assaults on the route, risks exacerbating tensions between Ukraine and its neighbours Hungary and Slovakia, who have accused Kyiv of trying to block oil flows through the pipeline to their refineries.
Shipments of Russian oil to Hungary and Slovakia have been cut off since January 27, when Kyiv says a Russian drone strike hit pipeline equipment in Western Ukraine.
Despite its nearly four-year-long war with Russia, Ukraine had continued to transport Russian oil through the pipelines across its territory even though it stopped the transit of Russian gas at the start of last year.
Hungary and Slovakia have both threatened to cut off electricity supplies to Ukraine if the oil flow does not resume.
Electricity from Hungary and Slovakia accounts for about 70% of Ukraine's imports and is extremely important for the country, half of whose power generation has been destroyed or seriously damaged by Russian missile attacks.
Hungary looked set on Monday to block further EU sanctions on Moscow and a 90-billion-euro loan for Kyiv, as attacks on Ukraine's southern Odesa region killed two people ahead of the fourth anniversary of Russia's full-scale invasion.
In a letter seen by Reuters, Hungarian Prime Minister Viktor Orban told European Council chief Antonio Costa the Druzhba outage was an "unprovoked act of hostility that undermines the energy security of Hungary" and vowed to block the loan until it was solved.
(Reporting by Tom Balmforth, writing by Anna Pruchnicka and Pavel Polityuk, Editing by Timothy Heritage and Andrew Heavens)
