The signing of a controversial gas deal between Russia and Ukraine has been delayed for a second time.
Ukraine has been hit by a cold snap that has caused dozens of deaths
Ukraine's Prime Minister Yuri Yekhanurov said experts were working on the details and would not be able to complete the agreement on Wednesday.
Ukraine has agreed to nearly double the price it pays for Russian gas after a bitter dispute earlier this month which left supplies temporarily suspended.
But the verbal agreement has led to political turmoil in Ukraine.
Parliament voted to dismiss the cabinet of President Victor Yushchenko, and the BBC's Helen Fawkes, in Kiev, says it is not clear who has the authority to sign the deal.
On Tuesday, the Ukrainian government ordered a cut in gas consumption after Russia accused it of tapping into supplies intended for European customers.
The suspension of gas supplies on 1 January disrupted supply to many European countries, as Ukraine is the main transit route for Russian gas.
A spokesman for Ukraine's state-owned energy firm Naftogaz said the excess gas was needed to cope with the especially cold January weather.
Temperatures have fallen lower than -30C in Ukraine, severely straining its energy infrastructure.
About 80 people have died as a result of the cold in the past week.
Under the five-year deal, Ukraine will buy Russian and Central Asian gas for $95 per 1,000 cubic metres on average.