Britain, which was hosting a meeting of G20 finance ministers in Scotland, was determined to push toward a $100 billion deal to cover the costs of climate change by 2020.
But talks got bogged down in a row with large developing countries about who should foot the bill.
There was a heated argument, Russian Finance Minister Alexei Kudrin said.
I think we should be very careful in approaching the possibility of piling big new commitments onto developing countries as this can put a brake on the pursuing of other crucial tasks such as the eradication of poverty.
The climate change discussion had dragged on for hours and a French official said the debate was so intense there was a risk the final statement would not mention climate change at all.
In the end, they agreed on the need to increase significantly and urgently the scale and predictability of finance to implement an ambitious international agreement.
European Union leaders agreed in October that developing countries would need 100 billion euros a year by 2020 to battle climate change.
About 22-50 billion euros of the total will come from the public purse in rich countries worldwide and the EU is expected to provide between 20 and 30 percent of that.
It's a bit disappointing because we would have liked to have done a little bit more work, said French Economy Minister Christine Lagarde, adding that Europe's offer was substantial.
China is often denounced by Western critics as the main obstacle to agreement, because it argues developing countries should not submit to binding international caps on emissions while they grow out of poverty.
In turn, China and other emerging powers have said the rich countries have done far too little in vowing to cut their own greenhouse gas output, and in offering technology and money to the Third World to help cope with global warming.
We have not come as far as we had hoped even this morning, said German Finance Minister Wolfgang Schaeuble.
We have not reached an agreement. There is still some work to do. I hope everybody knows that Copenhagen must not be a failure.
A European source said there was also frustration in a sunny St Andrews at the stance of the United States, who were sitting on the fence over climate change financing.
A 175-nation U.N. meeting in Barcelona ended on Friday with little progress toward a global deal on climate change but narrowed options on helping the poor to adapt to climate change, sharing technology and cutting emissions from deforestation.
The final U.N. preparatory meeting before Copenhangen re-opened a rich-poor divide on sharing the burden of curbs on greenhouse gas emissions and criticism of the United States for not tabling a formal, carbon-cutting offer.
About 40 world leaders will go to Copenhagen next month to improve the chances of clinching a climate deal, the United Nations has said.
British Prime Minister Gordon Brown, addressing the G20 delegates, said climate change was a test of global cooperation every bit as stern as the world financial crisis.
(Additional reporting by Gernot Heller and Jan Strupczewski, writing by Sumeet Desai and Patrick Graham; editing by Mike Peacock)