Copenhagen Climate Conference:

Arriving at the talks in Copenhagen, Todd Stern, the US chief negotiator, made it clear that he expected China to make considerable cuts in its carbon emissions despite being a "developing" country.

"The country whose emissions are going up dramatically – really dramatically – is China," he said. "You can't even think about solving this problem without having action from China. Our emissions are pretty much flattening out right now and then they're going down ... It's not a question of morality, just math."

He also shied away from the idea that American tax payers would help pay for China to move from dirty fossil fuels to clean coal – arguing that such a booming economy could do that itself.

"China has a dynamic economy which has led to it sitting on $2 trillion of reserves," he said. "I don't envision public funds, certainly from the United States, going to China."

However Mr Stern did say that America would be willing to help poor developing countries to cut emissions.

Xie Zienhua, China's chief negotiator, said China was willing to play a constructive role at the talks. The country has pledged to cut greenhouse gases 40 per cent against business as usual.

He said that China could accept a target to halve global emissions by 2050 if developed nations stepped up their midterm targets and agreed to provide financial help to the developing world to fight climate change.

But he wanted the Americans to do more for an agreement. "I do hope that President Obama can bring a concrete contribution to Copenhagen," he added.

At the moment the Americans have pledged to cut emissions 17 per cent against 2005 levels.