The UN's climate change summit is in chaos.
Major nations have reached what they call a "meaningful agreement" in Copenhagen.
But a number of developing nations say it is a failure and a betrayal.
The US reached a deal late last night with India, South Africa, China and Brazil to limit the increase in global temperatures to two degrees.
Up to 30 countries and the European Union have backed the deal but it is not legally binding.
President of the European Commission Jose Manuel Barroso says the deal is "clearly below our ambitions''.
The plan announced by the US includes $100bn a year in aid from 2020 for developing nations.
Sudanese diplomat Lumumba Di-Aping, the chief negotiator at Copenhagen for the G77 group of poorer countries, compared the agreement involving the US, China, India, South Africa and Brazil with the Holocaust.
The agreement “asks Africa to sign a suicide pact, an incineration pact, in order to maintain the economic dominance of a few countries”, said Mr Di-Aping.
He described the deal as “devoid of any sense of responsibility or morality... a solution based on the same values that funnelled six million people in Europe into furnaces”.
Jonathon Porritt, the former chairman of the Government’s Sustainable Development Commission, said the “big five” agreement was the result of “miserable self-interest and lowest common denominator politics”.
Mr Porritt said: “It is a fantastically bad outcome and it will be very disappointing for the UK, which has worked tirelessly over the last couple of years to try to avoid exactly this sort of debacle.
“To call it ’a start’ is trying to put a very brave face on things.
“What we have actually seen over the last two weeks is raw industrial power at its worst, both on the part of China and the US and other countries. They have not given an inch in terms of understanding the needs of some of the poorer countries.”