EU countries remain on alert for further disruption to their gas supplies after Russia cut off Ukraine in a row over pricing, and accused it of stealing gas bound for western markets.
The EU's fear of disruption to its gas supply became a reality last night, when Romania's pipeline operator said supplies had fallen by 30% to 40% that day and Hungary and Poland also reported drops.
But there was no immediate sign the problem had spread further.
The Czech pipeline operator said there were no problems in a main pipeline to Germany, Europe's biggest economy.
The Russian state-controlled gas monopoly, Gazprom, halted supplies to Ukraine on New Year's Day, saying Ukraine had failed to pay its gas bill and talks on 2009 gas prices had broken down.
The EU, which gets a fifth of its gas from pipelines that cross Ukraine, said it would call a crisis meeting of envoys in Brussels on Monday and demanded that transit and supply contracts be honoured.
Ukrainian President Viktor Yushchenko has angered the Kremlin by trying to join the NATO military alliance.
Russia and Ukraine have insisted they will honour their commitments but Gazprom said Ukraine was stealing gas destined for Europe, a charge Ukraine's state-run gas company denied.
Europe has enough gas stockpiled to manage without Russian supplies for several days but could face difficulties should problems last for weeks, analysts said.
