Belarus has said it will cut off pipes supplying gas from Russia to Europe and start to siphoning off supplies in a move that marked a sharp escalation in the "gas war" with the Kremlin.
Andrew Osborn in Moscow
If Belarussian President Alexander Lukashenko carries out his threat, the shut-off threatens to deprive the European Union of just over six per cent of its gas imports and will force Russia to find alternative ways of supplying Germany, Poland, Lithuania and its own Kaliningrad exclave.
Russia sends about a fifth of the gas it supplies to Europe through Belarus.
The move is retaliation for the decision on Monday by the state-controlled Gazprom and Russian president, Dmitry Medvedev, to reduce supplies to Belarus by up to 85 per cent, over a $200 million (?125 million) energy bill.
Mr Lukashenko said he was fed up with the Kremlin's disrespectful treatment of his country and said the dispute would only be resolved when Russia paid what he claimed was a big bill for the privilege of using his country as a conduit. He said that he felt humiliated by earlier comments from Mr Medvedev who said that Moscow only wanted hard cash and did not want to be paid for its gas in "pies, butter and cheese".
"The Russian leadership's statement humiliates the Belarussian people," said Mr Lukashenko. "I am sorry, when they start humiliating us with either cutlets or sausages or butter or pancakes, we perceive this as an offence to the Belarussian people."
Mr Lukashenko said: "I ordered the government to cut the transit via Belarus until Gazprom pays for transit." He said the dispute was turning into a "gas war".
Following Mr Lukashenko's threats, Gazprom vowed minimal disruption, saying it would not let others suffer for what was a bilateral payment dispute. It said it would pump extra gas via Ukraine if it had to in order to ensure there was no shortfall.
"We do not see any problems," Sergey Kupriyanov, a Gazprom spokesman said.
"Our clients in Europe will receive the necessary volumes.".
The EU was watching closely, saying it expected all gas contracts to be honoured. The dispute is reminiscent of a row between Russia and Ukraine in 2009 that caused misery across Europe and damaged Russia's reputation as a reliable energy supplier. But this time round demand for gas is lower in Europe due to the warm weather. The threat to European supplies is less serious because Belarus does not carry nearly as much gas to the EU as Ukraine.
Analysts said the standoff smacked of Kremlin intrigue. "Gas is a way of pressuring Belarus economically," Alexei Makarkin of Moscow's Centre for Political Technologies said. The Kremlin wants Belarus to join a customs union with Russia and is unhappy that Belarus is sheltering Kyrgyzstan's deposed president Kurmanbek Bakiyev.