The prime ministers of Russia and Ukraine are to meet in Moscow in an effort to end the dispute disrupting supplies of Russian gas to Europe.
However, there are sharp divisions within Ukraine over whether to link transit supplies to supplies for Ukraine itself at the negotiations.
The EU has urged Russia and Ukraine to prove they are “credible” partners and said it was their “last chance”.
A bid to hold a Moscow gas summit on the same day appears to be floundering.
Some central and east European states have been reduced to rationing gas.
Others have been seeking alternatives to the pipelines carrying Russian gas via Ukraine.
Russia ceased supplies of gas to Ukraine on 1 January after talks on the price Kiev should pay in 2009 collapsed.
On 7 January, it stopped deliveries to Europe via Ukraine, saying it was forced to do so because Kiev was stealing the gas.
Ukrainian officials deny the allegation and accuse Russia of provoking the crisis.
Almost 20 countries in Europe have been affected by what is the worst energy crisis the EU has ever faced, the BBC’s Richard Galpin reports from Moscow.
Russian Prime Minister Vladimir Putin, fresh from a visit to Germany, one of Moscow’s biggest gas clients, is due to meet his Ukrainian counterpart, Yulia Tymoshenko, on Saturday afternoon.
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