The prospects of a global deal to tackle climate change diminished last night after a senior US official played down the chances of President Obama attending December’s UN summit in Copenhagen .

Todd Stern, US Special Envoy for Climate Change, said that President Obama would go to Copenhagen only if sufficient progress was being made in the negotiations.

Last week Ed Miliband, the Energy and Climate Change secretary, appealed to President Obama to intervene to rescue the deal and said his presence in Copenhagen could make the all the difference between success and failure.

Mr Stern, speaking in London, said: “These meetings are always structured, just as Kyoto, to be held at ministerial level. We are not writing anything off or foreclosing possibilities but we treat this as a ministerial meeting in the first instance and if the kind of progress is made that would warrant the attendance of leaders then certainly we would consider that.”

President Bill Clinton did not attend the Kyoto negotiations in 1997 and the US never signed the Kyoto Protocol.

Mr Stern was attending the Major Economies Forum in London, where 17 countries attempted to resolve differences over the content of the proposed Copenhagen deal.

Mr Stern delivered a warning to developing countries that they needed to make substantial commitments on reducing the growth of their Greenhouse Gas emissions. “We don’t in the US deny that we have real historical responsibility but the IEA [International Energy Agency] in Paris will tell you that 97 per cent of the growth in emissions between now and 2050 will come from the developing world. The US has to act and the EU and Japan but also the developing countries. It’s the only way to solve this problem.”

Mr Stern added that the US wanted to be sure that developing countries would “stand behind,” any commitments that they made.

Mr Stern declined to say whether the US would itself make a binding commitment to cut emissions by a significant margin at Copenhagen. He said: “We are working very hard to move Senate legislation forward and we don’t want to speculate on what might happen if it doesn’t get all the way.”

He added that the Senate Bill, if passed, would result in a “seismic shift” in the US economy. It would commit the US to cutting its emissions by around 20 per cent by 2020 and 20 per cent each decade after that up to 2050. “That’s by every measure quite comparable to the EU.”

Mr Miliband last night repeated his plea for world leaders to take part in the negotiations. He said: “Leaders themselves need to be involved in these decisions.”

No new commitments were made at today’s meeting from any country either on reducing their carbon dioxide emissions or on how much they would contribute to a global fund to help developing countries adapt to climate change.

Mr Miliband said the key commitments from each country were only likely to be made in the final hours of the two week conference in Copenhagen. He said: “One of the last things to be agreed at these negotiations will be the precise numbers on finance and mitigation. These are the things slotted in at the end.”

Mr Miliband said there needed to be a clear process for establishing whether countries were meeting their commitments. “There needs to be a transparent sense that people can see what other countries are doing.”

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