The EU executive said Moscow's approval was a "huge success" in the international fight against climate change.

"It's a very happy day for Europe and for me," said Margot Wallström, the Swedish EU environment commissioner. "It sends a very forceful signal to the rest of the world. It is also very much a victory for the European Union."

Russia's ratification is vital for transforming Kyoto from a draft 1997 agreement into a working international treaty, despite its rejection by Washington in 2001.

Moscow has for years hedged on whether it would approve the pact, named after the ancient Japanese city where it was agreed in 1997.

The protocol requires industrialized signatories to cut output of six "greenhouse" gases by 2008-2012 compared with their 1990 levels.

Parliamentary ratification still needed

Commission spokesman Reijo Kemppinen conceded that "the final confirmation of this act will naturally only come once the parliament has formally ratified the Kyoto Protocol.

"But we are confident that they will do so in due course, in the coming weeks, given that the government and the president of Russia enjoy a majority in that house," he said.

"This is a huge success for the international fight against climate change," Commission President Romano Prodi said. "Today President Putin has sent a strong signal of his commitment and sense of responsibility."

"I have always held the view that this is in the best interest of Russia and its people," he added. "Global climate change is a fight that our generation has to win for the sake of the future of our children and this planet."

Wallström agreed that the world will have to wait for the Duma decision "before we can open the champagne bottles. But at least we can look at them today."