Accord signed in Russia gas row
Russia and European Union officials have signed a deal, which could pave the way for the re-opening of gas supplies to Europe.
The deal, signed by Russian PM Vladimir Putin and Czech PM Mirek Topolanek, sets out how gas flowing to Europe through Ukraine will be monitored.
Hundreds of thousands of European homes have no heating after gas shipments via Ukraine were halted on Wednesday.
The Czech PM is going to Ukraine, which must sign the deal if it is to work.
'Calming Russian fears'
The deal followed five hours of talks between Russian Deputy Prime Minister Igor Sechin and officials from the European Union.
"Let's sign and we will go immediately to Kiev to ask the same of the Ukrainian side. And so, we will end the crisis," said Mr Topolanek, who represented the EU.
Ukrainian Prime Minister Yulia Tymoshenko's office says she will meet with Mr Topolanek in Kiev at 2030 local time, 1830 GMT.
The Ukrainian prime minister will meet for talks on the crisis later on Saturday
Under the deal, EU, Ukrainian and Russian observers will monitor supplies, in order to calm Russian fears that Ukraine is siphoning off gas for its own use. Ukraine has denied this allegation.
Mr Putin is quoted on Interfax, the Russian news agency, as saying that the "transit of gas through Ukraine will start again as soon as the (transit) control mechanism starts to work".
EU monitors are in Kiev and are expected to head to the pumping and measuring stations on Ukraine's eastern and western borders early on Sunday, a spokesman for Naftogaz, the Ukrainian state energy company, told the BBC.
Even if a deal goes through, the affected countries are unlikely to have gas before Monday at the earliest.
Ukraine and Russia's bitter contractual dispute over gas prices and transit fees has affected several countries.
Although both countries had guaranteed that transit supplies to Europe would be unaffected, they were cut off amid mutual accusations between Kiev and Moscow.
More than 15 countries across central Europe have been hit by the shutdown of Russian supplies.
The EU gets a quarter of its gas supplies from Russia, 80% of which passes through Ukraine.
Serbia and Bosnia-Hercegovina are among the worst hit as many homes rely on heating stations that only run on gas