Belarus has halted Russian oil supplies to Poland, Germany and Ukraine after a trade row with Moscow escalated, BBC reports on Monday.
Disruptions hit Transneft's Druzhba pipeline overnight before supplies were severed completely at Poland's border with Belarus, Polish officials said.
The problems arose after Belarus began legal action against Transneft for failure to pay a new oil shipment tax on oil supplies piped through Belarus.
It signals the latest twist in an energy row between Belarus and Moscow.
The dispute began after Russian energy giant Gazprom forced Belarus to accept a huge increase in the price of Russian gas.
Russia has called for an end to the oil shipment tax saying it threatens supplies to Europe.
Every day Russia transports about a fifth of its oil exports - or one million barrels - through Belarus, mainly to refiners in Poland and Germany.
Oil supplies via the Druzhba pipeline to Poland and Germany were halted overnight. We sent a letter to Belarus asking for explanations," said Tomasz Zakrzewski, a spokesman for Polish pipeline operator PERN.
Poland's deputy economy minister, Piotr Nalmski, said that the supply problems were a result of the trade row, while adding that the country had sufficient oil reserves for 80 days.
"This shows us once again that arguments among various countries of the former Soviet Union, between suppliers and transit countries, mean that these deliveries are unreliable," he told the BBC.
Germany said supplies to its Leuna and Schwedt refineries in eastern Germany had also been halted.
Michael Glos, German Economy Minister, said he viewed the pipeline closure with concern and called on Russia and Belarus to meet their energy transit and delivery responsibilities.
"I expect the deliveries through the pipeline to resume completely as soon as possible," he said.
However, officials in Minsk declined to comment on the situation, saying all questions should be directed to Transneft.
Meanwhile, Transneft said it was doing all it could to boost supplies from via other routes.
Further reports suggested that the company had also accused Belarus of siphoning off Russian oil destined for Europe from the pipeline.
The cut off in oil supplies is the latest twist in a row between Moscow and Minsk over energy prices.
Last week Belarus said it would charge Russia $45 (£23) per tonne of oil that passed through its country.
The tit-for-tat tax move was introduced by the Belarusian government days after the country was forced to accept a doubling of Russian gas charges - from $47 to $100 - when Moscow threatened to cut supplies if Belarus refused to agree new prices.
News of the disruption to supplies was a key factor helping to drive oil prices closer to the $57-a-barrel mark on Monday after falling to around the $55 level last week.
(BBC News, 08/01/2007)