About 45 countries are due to attend the informal ministerial conference on September 2 to 3, including Brazil, China, South Africa and the United States, said Franz Perrez, head of international affairs at the Federal Environment Office.

Several ministers have so far confirmed their presence in Geneva, including from Britain, Germany, Singapore, while the United States is sending its special climate envoy, he told AFP.

Key long-term financing issues include a new fund for the environment, ways to bring the private sector into financing, coordinating funding and finding new sources of finance.

Perrez emphasised that the talks were "not part of the official UN negotiations on climate change," but jointly organised with Mexico under its attempts to broker a deal at the conference later this year.

The UN climate talks in the Mexican city of Cancun from November 29 to December 10 are aimed at achieving a bolstered agreement on carbon dioxide emissions to replace the Kyoto Protocol which expires in December 2012.

A similar attempt in Copenhagen last December failed to achieve more than a limited, non-binding political accord.

It included a pledge for long-term financing to help poor countries green their economies and cope with consequences of climate change, without specifying where the money would come from.

Perrez said the Geneva meeting would hear the first results of a study ordered by the Copenhagen conference on finance for developing nations.

Delegates from rich and developing nations warned after official preparatory negotiations in Germany on August 6 that the overall talks under the 194-nation UN Framework Convention on Climate Change (UNFCC) were losing ground.