Blair, speaking in parliament, defended Britain's overall efforts to combat global warming, saying it was one of the few countries which was on schedule to comply with carbon dioxide (CO2) emissions reductions in line with the Kyoto Protocol.

Under the terms of the Kyoto Protocol -- the world's most ambitious environmental treaty, negotiated in 1997 but boycotted by the United States -- Britain must reduce its greenhouse gas emissions, especially CO2, by 12.5 percent compared with 1990 levels by 2008-2012.

Blair's Labour government, which has pledged to make climate change a priority, has gone even further, vowing to cut its emissions of greenhouse gases by 20 percent by 2010.

Blair said according to current trends Britain would make a 14-percent reduction by that date, but did not exclude the possibility that further environmental regulation could help reach the domestic target.

"We have years to go before we have to achieve that (20-percent) target.... We don't accept we won't meet it. We've got to make sure that we take the measures to meet it," the prime minister said.

The government review announced Wednesday says there were further "opportunities" for carbon emission reduction, notably through greater household energy efficiency, a rise in the use of biomass for farming and better public transportation services.

Also, it heralded the new EU emissions trading scheme, which will allow members of the 25-nation bloc to buy and sell credits for carbon dioxide emissions, thereby allowing richer nations like Britain to "buy" the pollution credits of a less-polluting country in return for cash.

Margaret Beckett, a junior minister for the environment, food and rural affairs, said any revisions of the climate change policy would be made public in the first half of 2005.

Negotiations on the Kyoto Protocol were meanwhile underway in Argentina, at an annual UN conference. Following Russia's ratification of the treaty in December, it will take effect in February.

But for all its diplomatic and economic import, and the changes to rich nations' environmental policies, the treaty will have a minimal impact on the climate.

The gases it regulates, products primarily of burning oil, gas and coal, can persist in the atmosphere for hundreds of years, and are already heating up the planet.

Scientists say that reductions of around 60 percent are urgently needed to avoid wreaking potentially catastrophic damage to the world's economies. The present so-called commitment period under Kyoto runs out in 2012.

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