Having signed the treaty, which had previously been blocked due to the need for either Russia or the United States to ratify it, Putin is now due to notify the United Nations of his country's approval of the pact, aimed at cutting the pollution emission that cause global warming of the world's atmosphere.

According to Kremlin officials, Russia's ratification of the treaty will become effective three months after Putin has notified the UN of the move.

Backed by 126 countries, the climate pact is aimed at curbing global warming and can now come into force early next year, 90 days after the Russian ratification documents are filed with the UN.

US not on board

The treaty was adopted at a UN conference on climate change in 1997, but the US, which accounts for 36 percent of emissions and is the world's number-one emitter of greenhouse gases, pulled out in 2001, making the treaty dependent on Russian ratification.

The pact commits the developed nations to cut overall emissions of heat-trapping carbon dioxide by 5.2 percent below 1990 levels by 2008-12, by curbing use of coal, oil and natural gas and introducing cleaner energies like solar and wind power.

To come into force, the it needed to be ratified by countries accounting for at least 55 percent of developed nations' greenhouse gas emissions. Russia accounts for 17 percent of world emissions.

As he begins his second presidential term, George W. Bush has signalled no intention of changing Washington's bullish stance on Kyoto.

Russian doubts

Russia signed the Kyoto Protocol in 1999 but has been dragging its feet in recent years over ratification. Leading Russian scientists claimed there was no evidence linking greenhouse gas emissions to climate change, while the Kremlin was also anxious about economic cost and sceptical of the Protocol's impact.

It finally agreed to ratify in exchange for EU agreement on terms for Moscow's admission to the World Trade Organization.