At the same time Vladimir Chizhov, Russia's ambassador to the European Union, floated the idea that Gazprom, Russia's state-owned gas monopoly, might form a consortium with Ukrainian and EU partners to oversee Russian gas deliveries to Europe.
Mr Chizhov was speaking to reporters ahead of talks in Moscow on Friday between Vladimir Putin, Russia's prime minister, and José Manuel Barroso, the European Commission president.
Nine other EU commissioners will attend the discussions, the first such face-to-face talks since Russia cut off Europe's gas supplies through Ukraine in early January after a dispute over the contract governing Gazprom's deliveries to the Ukrainian domestic market.