UNITED NATIONS: The world's leading economies must deliver on their promise to raise $100 billion for climate financing by 2020, UN Secretary-General Ban Ki-moon has said.

Developing countries are demanding a clear commitment to the financial contribution agreed during the Copenhagen summit in 2009 as part of the climate deal being negotiated in Paris.

"I have been urging the developed world leaders that this must be delivered," Ban told reporters at UN headquarters.

"This is one very important promise."

Negotiators from 195 nations are haggling in Paris over a universal accord to slash greenhouse-gas emissions but the G77 group of developing countries plus China have warned there will be no deal without financing.

The poorer nations are seeking billions of dollars to help them make the shift to cleaner energy sources and build resilience to the impacts of global warming.

Ban said that of the $100 billion to be mobilized by 2020, $62 billion has been raised.

"Now we have another five years to go. And everybody said that it is doable, and it can be presented in a credible way," he added.

The dispute over climate financing has revolved around the sources of financing, which would be shared among governments, international institutions like the World Bank, and other private and public sources.

More than 150 world leaders including U.S. President Barack Obama launched the talks, hoping to seal the landmark deal by December 11.

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