World powers will not agree to firm targets for cutting greenhouse gas emissions during the G8 summit, a senior US official has said.
World leaders are meeting in Heiligendamm on the Baltic coast for the annual Group of Eight gathering which comprises of Britain, Canada, France, Germany, Italy, Japan, Russia and the United States.
Chairing the summit, German Chancellor Angela Merkel had hoped the US would back a pledge to have emissions halved by 2050 and limit warming of global temperatures to a key scientific threshold of 2C.
The Kyoto Protocol, the global climate change pact which the US is not a part of, expires in 2012 and leaders hope the summit can send a signal about their desire to come up with a successor to the deal.
Senior climate adviser to President George W Bush, James Connaughton, said: "We have opposed the two degrees temperature target, we are not alone in that.
"Japan, Russia, Canada and most other countries that I have spoken with do not support that as an objective for a variety of reasons. At this moment in time on that one particular issue we do not yet have agreement."