Poland, Hungary, Romania and Bulgaria have reported drops in supplies by as much as 40 percent after Russian state-controlled gas export monopoly Gazprom cut off Ukraine on New Year's Day in a row over prices.

Germany, Europe's biggest economy, has so far not seen supplies drop. The European Union, which gets about a fifth of its gas from pipelines that cross Ukraine, has demanded that transit and supply contracts be honoured.

But Russia and Ukraine's gas companies traded allegations throughout Saturday, indicating the prospect of a swift resolution to the row could be remote.

Gazprom said Russian President Dmitry Medvedev had approved its move to take Ukraine's state-run gas company to the arbitration court in Stockholm over gas transit to Europe.