The countries are currently negotiating payment of Ukraine's debt, which Gazprom earlier quoted at $2.4 billion. Some of the funds have reportedly been paid, but Gazprom has demanded full payment, and threatened supply cuts.
Gazprom spokesman Sergei Kupriyanov said he cannot reveal how much of the debt is outstanding, but that Ukraine has "not paid in full, and has asked for a postponement."
He said that as of December 1, Ukraine was scheduled to have paid $550 million. He said talks on whether to postpone the repayment schedule would continue on Wednesday.
A spokesman for Swiss trader RosUkrEnergo said Tuesday that Naftogaz had transferred to gas intermediary RosUkrEnergo $268.7 million of the $550 million.
Ukraine currently pays $179.5 per 1,000 cubic meters for gas imported from Russia or via Russian territory.
Russian Prime Minister Vladimir Putin and his Ukrainian counterpart Yulia Tymoshenko agreed at the start of October on a memorandum for direct gas supplies from Gazprom and Naftogaz with a gradual shift to market prices. The full repayment of Ukraine's gas debt was fixed as a condition.
Gas pricing and supply has been a thorny issue in recent years, triggering bitter rows between the two former Soviet republics.
A gas pricing row between the countries at the start of 2006 led to a brief cut in supplies to Ukraine, which also transits about 80% of Russia's Europe-bound gas. Some consumers in Europe reported a decline in supplies during the dispute.
