ST. ANDREWS, Scotland -(Dow Jones)- Finance ministers from the Group of 20 leading economies were struggling to agree on climate change issues at their meeting Saturday, with big developing economies reluctant to make commitments before broader talks in Copenhagen next month.

The apparent lack of progress on climate issues doesn't bode well for the United Nations summit in Denmark in December, where nations hope to agree a new global deal to tackle global warming.

A Brazilian government source said Brazil, India and China didn't want to agree new financial commitments at a finance minister level at the G20 summit while climate negotiations were going on elsewhere, adding that talks went on until 0600 GMT before ending at an impasse.

"This isn't the forum for these [climate] talks," the person said.

The weekend's G20 meeting in Scotland was tasked with making progress on the issue of financing efforts by developing countries to combat climate change. This included ensuring that any financial support given to developing nations would be used wisely.

Speaking at the G20 talks, U.K. Prime Minister Gordon Brown said he had no illusion about the scale of the challenges policymakers still faced ahead of the Copenhagen meeting.

"It is a historic moment: a test of global cooperation every bit as significant as the economic tests we have faced together this year," Brown said. "It is essential that we urgently move toward resolving the issues that still divide our nations."

Earlier Saturday, U.K. Chancellor of the Exchequer Alistair Darling said it is "imperative that when we reach the end of the day we show real progress...If there isn't an agreement on finance, negotiations in Copenhagen will be much more difficult."

A source in one of the delegations from the Group of Seven leading developed economies also said Saturday that progress on climate change looks very difficult because developing countries are throwing up roadblocks.

On Friday an official from the French Finance Ministry separately told reporters there was no guarantee the final communique of the G20 meeting would even mention the issue of climate change.

-By Nicholas Winning, Dow Jones Newswires, +44 207 842 9498; nick.winning@dowjones.com

(With reporting by Laurence Norman and Nathalie Boschat.)

(END) Dow Jones Newswires

11-07-09 0855ET