The talks, which were heading to a close on Saturday, drew some 1,900 diplomats from 182 countries to Bonn to line up what their leaders will be prepared to sign up to next year to tackle emissions that U.N.-backed scientists say will cause more severe flooding, droughts and the sea level to rise.

 

Negotiators and observers said signs of action from China and the United States, the world's top two emitters, had raised hopes but they warned the talks could break down unless rich nations pledged billions of dollars in aid to poorer states by the end of the year.

 

"We are getting to the point where all parties have a sense of trust that we can act together to combat climate change, but my biggest concern is about the cash," said Seyni Nafo, a Malian envoy representing a negotiating bloc of over 50 African states.

 

Developed nations agreed in 2009 to raise aid to developing nations to $100 billion a year by 2020 but the U.N.'s "Green Climate Fund" set up to channel the cash lies empty after launching last month.

 

Nafo said $7-8 billion dollars in pledges were needed by the year-end to start projects such as installing solar power or insurance schemes to help farmers cope with crop failures.

Nations agreed last year that the deal, due to be struck in Paris in 2015 and to enter into force from 2020, would consist of a framework of contributions from all countries to be proposed early next year.

 

Negotiations over the past two weeks focused on what those contributions should include, such as having major economies setting emission reduction or peaking targets. Some said these should also include binding financial aid commitments by richer nations to support the poor.

 

But there was little headway on which countries should make the strictest contributions.