The Russian energy monopoly said on Monday it would reduce its delivery of gas to Ukraine by 65.3 million cubic meters - the volume that had been stolen.
Gazprom's CEO Alexei Miller said that Gazprom was ready to guarantee deliveries to Europe by buying gas on the spot market, and that as well as increasing transit volumes through Belarus, Poland and Turkey, Gazprom would increase volumes of gas taken from underground reservoirs in European countries.
Gazprom cut off gas supplies to Ukraine on Thursday after last-ditch talks with Kiev on a new deal for 2009 and debt repayments failed late on New Year's Eve.
Around 80% of Russia's gas exports to Europe pass through Ukraine, and some European countries, including Poland, Hungary, Bulgaria, and Romania, have reported drops in Russian gas supplied through Ukraine's pipeline network.
Miller has accused Naftogaz of tapping Russian gas, which Ukraine denied, blaming Russia for creating the shortfall by deliberately cutting deliveries to Europe.
With Ukraine's gas debt to Russia from 2008 unresolved and no contract agreed for 2009 deliveries, the issue of Russian gas flowing through Ukrainian pipes to European consumers further west has become contentious.
In response to a claim by Ukraine's energy ministry, the Kiev economic court ruled on Monday that Naftogaz could not pump Russian gas westwards at a price of $1.6 for 1,000 cubic meters per 100 kilometers.
Both Gazprom and Naftogaz have said that they will file lawsuits with the Stockholm Arbitration Court, which deals with international commercial legal disputes. The court on Monday said it could not comment on whether it was considering lawsuits from either party in the gas dispute.
