The possibility of binding emission cuts emerging from the UN's climate change conference in Bali receded significantly over the weekend after the US delegation rejected proposals for developed economies to cut emissions by between 25 and 40 per cent on 1990 levels by 2020.

In an unusual step, the UN published a draft of the agreement delegates have been working on over the past week. The document aims to set out a roadmap for negotiations over the next two years as the UN strives to get agreement on a successor to the Kyoto Protocol before it expires in 2012.

The draft included emission reduction targets for richer nations, but the US said it would reject set goals for emission reductions at this stage, with Japan also reported to be opposed to the idea.

Speaking at a press conference, the US chief negotiator said that Washington wanted a roadmap for future negotiations to be agreed before the talks end on Friday, but was insistent that discussions on binding emissions targets should be left to a later date.

"We don't want to start out with numbers," he said, adding that the 25 to 40 per cent range recommended by the UN's panel on intergovernmental panel on climate change and backed by European negotiators was guilty of "prejudging" the outcome of future talks and was based on "many uncertainties".

However, the UN's top climate change official, Yvo de Boer, currently remains committed to the target, insisting that its adoption would send out a clear signal that legislators are committed to curbing global warming.

The news is likely to frustrate green business leaders who last week called for a clear regulatory framework built around an expansion of carbon t rading and binding emission reduction targets to be agreed as soon as possible. They argued that such an agreement was required to give investors certainty that expenditure on low-carbon technologies and business models will pay off.

De Boer also praised China and other large developing economies, which previously have been staunchly opposed to climate change legislation. He said that the Chinese delegation had been offering "very concrete, very specific ideas on how you could construct a post-2012 climate change regime".

The comments came as the Chinese government last week published a major new energy law designed to cut emissions, enhance energy efficiency and offer incentives to renewable energy technologies.

The Bali talks are to step up a gear this week, with world finance ministers scheduled to meet tomorrow and an agreement on the timetable for negotiations expected to be reached by Friday.

De Boer said there was now a consensus among industrialised nations that a roadmap had to be agreed this week that would ensure a replacement for Kyoto is agreed at UN talks in Copenhagen in late 2009.