The United States ruled out making extra pledges to fight global warming beyond 2012 today, angering environmentalists who accused Washington of blocking a 189-nation conference in Canada.
Chief US climate negotiator Harlan Watson also strongly defended President George W. Bush's environmental record, saying emissions by the world's biggest polluter had fallen more in 2000-2003 than in the European Union.
Up to 10,000 delegates are meeting in Montreal, Canada, from November 28th-December 9th to discuss new ways to fight a build-up of gases released mainly from burning fossil fuels in factories, power plants and cars.
"The United States is opposed to any such discussions," Mr Watson told a news conference of Canadian proposals to launch talks under the UN's climate convention about new actions to combat global warming beyond 2012.
Environmentalists accused Washington of doing too little to fight a rise in temperatures from human activities that could lead to more storms, expanding deserts and worse floods, and could raise sea levels by up to three feet (one metre) by 2100.
Bill Hare, climate policy director of Greenpeace, called the United States the "fly in the ointment" at the conference.
"The failure of the United States to be willing to discuss future action here is the real issue," he said, predicting Washington will only join a global pact after Bush leaves office.
Mr Bush pulled out in 2001 of the UN's Kyoto Protocol, under which about 40 industrial nations have to cut greenhouse gas emissions by about 5.2 per cent below 1990 levels by 1008-12.
At Montreal, Kyoto backers plan to launch talks, likely to last several years, on new commitments beyond 2012.
Mr Bush branded Kyoto too costly and said it wrongly excluded poor countries. Many also hope to start wider parallel talks among all countries, including the United States and developing nations such as China and India, on new ways to fight climate change.