Russia's cutoff of natural gas to Ukraine was forcing several European countries to dip into reserves Monday, with Moscow tightening the tap even further.
European Union officials gave assurances Monday that consumers faced no danger for now, even as Hungary, Romania and Bulgaria said that supplies from pipelines through Ukraine remained down, in Romania's case by 30 percent.
Russia's state-controlled gas giant Gazprom stopped supplies to Ukraine on Thursday in a dispute over price and overdue bills and said it would keep pumping gas through Ukraine for European customers.
But Gazprom CEO Alexei Miller said Monday it would cut the amount of gas going into the pipeline by 65.3 million cubic meters, or about 20% of what has been the daily supply, accusing Ukraine of having stolen that amount in recent days.
Miller said in a televised meeting with Prime Minister Vladimir Putin that such reductions would continue daily depending on the amount of gas not making it through Ukraine.
Ukraine says Gazprom has not been supplying the 25 million cubic meters of "technical gas" needed each day as fuel to send supplies westward, so it has been taking the gas.
Miller said Gazprom would take steps to compensate European consumers, in part by sending more gas through pipelines that cross Belarus and Turkey. He said Gazprom also would increase the amount taken from underground stores in Europe and buy gas on the spot market.