"He welcomes this step, since the entry into force of the Kyoto Protocol, made possible by Russia's ratification, will be the essential first step in tackling the planetary challenge posed by climate change," Annan's spokesman said in a statement.

"He takes this occasion to remind the entire international community of the need to bring a greater sense of urgency to this crucial issue of human security and well-being," the statement said.

Russia's ratification is vital for transforming Kyoto from a draft 1997 agreement into a working international treaty. Moscow had for years hedged on whether it would approve the pact.

The treaty requires industrialised signatories to trim output of six "greenhouse" gases by between 2008 2012 compared with their 1990 levels.

Russia's cabinet backed the treaty earlier Thursday, a key step that is likely to finally enable the measure to enter into force despite its categorical rejection by the United States.

The cabinet decided to send the treaty on to the State Duma lower house of parliament for approval, which is all but guaranteed in a chamber where the Kremlin holds a two-thirds majority.

Deputy Prime Minister Alexander Zhukov was quoted saying that the various Russian ministries will adopt the proper legislation required for the treaty to be formally ratified by Russia within three months.

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