The head of the UN panel of climate experts said yesterday he was "reasonably confident" that next month's summit in Copenhagen to work on a new global climate-change agreement would be a success.

"I'm reasonably confident that Copenhagen will be a success. I expect a commitment to be reached in Copenhagen, as a step for a strong agreement in Mexico," Rajendra Pachauri, who chairs the Intergovernmental Panel on Climate Change, told reporters in Madrid.

He was referring to a climate change summit proposed for Mexico next year in case the December 6-18 talks in Denmark fails to reach a final agreement.

Representatives from some 190 countries are set to take part in the Copenhagen talks, which aim to replace the Kyoto treaty that expires in 2012, and curb emissions of carbon dioxide and other gases scientists say will warm the planet.

Mr Pachauri praised the new carbon emissions targets proposed by the US and China, the world's two biggest carbon emitters, earlier this week which have breathed life into UN climate talks.

He said the US announcement "is certainly a very encouraging step forward, even if the targets announced are not as large as Europe and the world would like."

"During a long, long time they haven't done anything. But we must also realise that what has been said has not been ratified by the Congress."

US President Barack Obama set goals that would reduce US carbon emissions by 17 per cent by 2020.

China has vowed to cut carbon intensity, measured per unit of GDP, by 40-to-45 per cent from 2005 levels within a decade, putting its first-ever emissions targets on the table.

"I'm glad that China has made a commitment which I should see as a first step, a significant step. I think that China's step is an important first step," said Mr Pachauri.