World leaders back delay to final climate deal

"The problem is the United States, there's no doubt about that," Borloo, who has coordinated France's Copenhagen negotiating effort, told Reuters in an interview.

"It's the world's number one power, the biggest emitter (of greenhouse gases), the biggest per capita emitter and it's saying 'I'd like to but I can't'. That's the issue," he said.

Danish and Swedish officials said they wanted all developed countries including the United States to promise numbers for cuts in emissions in Copenhagen. The U.S. Senate has not yet agreed carbon-capping legislation.

"There was an assessment by the leaders that it was unrealistic to expect a full, internationally legally binding agreement to be negotiated between now and when Copenhagen starts in 22 days," said U.S. negotiator Michael Froman.

"We believe it is better to have something good than to have nothing at all," said Chilean Foreign Minister Mariano Fernandez. The next major U.N. climate meeting is in Bonn in mid-2010.

"Copenhagen can and must deliver clarity on emission reductions and the finance to kickstart action. I have seen nothing to change my view on that," said Yvo de Boer, the U.N.'s top climate change official. Ministers from 40 nations will meet in Copenhagen on Monday and Tuesday for preparatory talks.

Copenhagen was seen as the last chance for countries to agree on a successor to the Kyoto Protocol, aiming to fight a rise in temperatures that many scientists predict will bring rising sea levels and more floods and droughts.

The aim of the summit is to set ambitious targets for cutting greenhouse gases in industrialised nations, but also to raise funds to help poor countries slow their own emissions growth and tackle the worst impacts on crops and water supplies.

But negotiations have been bogged down, with developing nations accusing the rich world of failing to set themselves deep enough 2020 goals for curbing greenhouse gas emissions.