Todd Stern, the US's climate change envoy, has warned countries such as China and India that they run greater risk of protectionist measures in the US Congress if they do not co-operate on international steps to hold down carbon emissions.

Speaking to the FT, he added that the US would still have a solid bargaining position even if, as is widely expected, the Obama administration fails to push its own emissions legislation through Congress before December's intergovernmental conference at Copenhagen.

Asked about pressure from US legislators to incorporate protectionist measures into the cap-and-trade bill, which has passed the House of Representatives but not the Senate, Mr Stern, said: “The more there is a sense that the big countries are recalcitrant or unwilling to step up then the greater the pressure in Congress is going to be in that direction.”