Russian President Dmitry Medvedev says an agreement negotiated on Sunday to resume gas supplies to Europe via Ukraine is void.
Mr Medvedev said he received a copy of the agreement signed by Ukraine, but an attached declaration contradicted the Russian position.
A short time earlier, Russia, the Ukraine and the European Union signed a gas monitoring deal intended to restart the flow of Russian gas through Ukraine to Europe.
Hundreds of thousands of European homes are without heating after Russia stopped its gas shipments through Ukraine on Wednesday as a result of a bitter contractual dispute over gas prices and transit fees.
More than 15 countries across central Europe have been hit by the shutdown. The EU gets a quarter of its gas supplies from Russia, 80% of which passes through Ukraine.
Russian Prime Minister Vladimir Putin had said gas flows would resume as soon as international experts began monitoring the pipeline.
The deal, signed by Ukraine, Russia and the Czech Republic, had set out how gas flowing to Europe through Ukraine would be monitored.
The deal, struck after five hours of talks, aimed to calm Russian fears that Ukraine was siphoning off gas for its own use, an allegation Ukraine has denied.
