The US on Thursday played down differences on climate change with the other Group of Eight industrialised nations, amid claims by environmental campaigners that a leaked “plan of action” showed the US was blocking progress in the run up to next month's Gleneagles summit.

Tony Blair, the British prime minister, has made tackling climate change a priority for the UK's G8 presidency but the June 14 version of the Gleneagles declaration appears weaker in several respects than previous drafts.