Four European gas buyers have already paid for supplies in roubles as Russia demanded and further cut-offs if others refuse the Kremlin's requirement aren't likely until the second half of May, when the next payments are due, according to a source close to Russian gas giant Gazprom.

Ten European companies have already opened the accounts at Gazprombank needed to meet president Vladimir Putin’s payment demands, the source said, speaking on condition of anonymity to discuss confidential matters.

Supplies to Poland and Bulgaria were cut off on Wednesday after they refused Gazprom's proposed mechanism for rouble payments, which the gas giant says does not violate European Union sanctions, according to the source. Russia supplies gas via pipelines to 23 European countries.

After the EU imposed sanctions on Russia over its invasion of Ukraine, Moscow demanded that it be paid in roubles for shipments starting on April 1st. But the bloc told member states that the mechanism the Kremlin proposed, which required opening euro and ruble accounts with state-controlled Gazprombank, would violate the sanctions. – Bloomberg