"We have faced an undisguised theft of Russian gas by Ukraine," Gazprom first deputy Alexander Medvedev said Tuesday, RIA Novosti reported.

Russia cut deliveries to Ukraine Jan. 1. Russian Prime Minister Vladimir Putin on Monday ordered the state-run Gazprom to cut supplies another 20 percent, the amount Gazprom Chief Executive Officer Alexei Miller said Ukraine was siphoning off to make up for the original delivery reduction.

European customers are now caught up in the dispute, which revolves around Gazprom's claim that Ukraine owes $600 million on its energy bill and an unsigned 2009 contract.

Bulgaria and Turkey said their deliveries were halted. The Czech Republic, Greece, Macedonia and Romania have also reported supply disruptions, The New York Times reported.

The European Commission and the European Union presidency have demanded swift resolution to the dispute.

Ukraine accused the Kremlin of using the issue to advance a political agenda.

Medvedev said Ukraine was not negotiating, but "there is only one way out: The lacking contracts on gas deliveries should be signed and Ukraine should ensure transit," he said.