Environmentalists accused the Bush administration of trying to derail the UN Climate Change Conference after the US said that it would resist any binding commitments to curb global warming through industrial emissions caps.
Harlan Watson, chief climate control negotiator for the US State Department, told a news conference the US would maintain its position of rejecting any calls for an international agreement that binds countries to emissions reductions after 2012.
The US belongs to the 1992 UN Framework Convention on Climate Change, a pact by 190 signatories, which has no binding caps on industrial emissions.
Mr Watson said no binding agreements under the convention should be conducted in Montreal.
"Formalised discussions under the Framework Convention, which is the current proposal by some parties, are in faction negotiations," Mr Watson said.
"The United States position remains consistent: We see no change in current conditions that would result in the negotiated agreement consistent with the US approach."
Mr Watson said the US would continue with its voluntary efforts to curb global warming via science, technology and bilateral agreements with other nations.
He said greenhouse gas emissions had actually gone down nearly 1 per cent under Mr Bush's first three years in office.
"We need to pursue our international efforts in a spirit of cooperation - not coercion - with a true sense of partnership," Mr Watson said.
Mr Watson told The Associated Press that the Bush administration does not blame global warming or climate change for extreme weather events, including the hurricanes that ravaged the Gulf Coast states and much of the Caribbean and Yucatan Peninsula.
"There's a difference between climate and extreme weather," Watson said.
"Our scientists continually tell us we cannot blame any single extreme event, attribute that to climate change."
Environmentalists angry
This notion infuriates environmentalists, who point to myriad studies which they believe proves global warming is to blame for rising, warmer seas, melting Arctic glaciers and extreme weather conditions.
"This is a wildly irresponsible position," said Bill Hare, of Greenpeace International who is also a physicist with the Potsdam Institute for Climate Impact Research in Germany.
"It's scientifically wrong. The evidence on climate change is growing literally every week," Mr Hare said.
He said the lack of US commitment to mandatory greenhouse gas reductions was the single biggest complaint among conference delegates.
"When you walk around the conference hall here, delegates are saying there are lots of issues on the agenda, but there's only one real problem, and that's the United States," he said.
Alden Meyer of the US-based Union of Concerned Scientists, said the 18 per cent reduction of greenhouse gases used by the White
House is really part of "a shell game to fool people."
He said that as Americans upgrade to new cars and home appliances, and industries make improvements at factories, the emissions of carbon dioxide will naturally decline.
But economic growth per capita, without mandatory emissions caps, means the US is expected see a 30-per cent hike in greenhouse gas emissions over 1990 levels by 2012.
Mr Meyer applauded the Bush administration for its massive spending on science and technology to find less polluting alternative energy sources, but said the results would come too late.
"They have no strategy to deal with moving these technologies into the market quickly enough to deal with global warming," he said.
Kyoto treaty
The Kyoto Protocol, negotiated in Japan's ancient capital of Kyoto, targets carbon dioxide and five other heat-trapping gases blamed for rising global temperatures and disrupting weather patterns.
The treaty, which went into effect in February, calls on the top 35 industrialised nations to cut emissions by 5.2 per cent below their 1990 levels between 2008 and 2012.
More than 8,000 environmentalists, scientists and government officials were attending the 10-day conference in the French-speaking city of Montreal.
About 120 environment ministers and other government leaders were expected there next week for the final negotiations.
This conference will set agreements on how much more emissions should be cut after 2012, when the second phase of the protocol begins.
The 140 countries that ratified the treaty were meeting for the first time since Kyoto was adopted in 1997, and were preparing to officially implement regulations under which the treaty must be carried out.
The United States, the world's biggest emitter of polluting gases, refused to join the Kyoto accord, with President George W Bush saying the treaty's emissions caps would be detrimental to the US economy.
Instead, he called for a US reduction of greenhouses gases of 18 per cent by 2012 and has committed $US5 billion ($A6.78 billion) annually on science and technology to combat global warming.