Negotiations over setting up the Green Climate Fund (GCF) suffered setbacks after the U.S. rejection of a proposal at the ongoing climate talks in Durban, South Africa.

The debate on setting up the much-anticipated GCF started Wednesday at the 17th Conference of Parties to the United Nations' Framework Convention on Climate Change (COP 17).

The U.S. delegation has rejected a proposal on how to raise 100 billion U.S. dollars for poor countries to develop low-carbon economies.

The U.S. rejection, together with reservations from some other countries, broke the broad consensus that the draft fund, while imperfect, could be adopted and operational soon after next year's talks in Qatar, observers said.

Host country South Africa once had high hopes on setting up the GCF, and the country's Foreign Minister Maite Nkoana-Mashabane said the success of the Durban talks depends on setting up the fund.

After the setbacks, South Africa's Environmental Affairs Minister Edna Molewa indicated there had been no sign of any compromise among conflicting parties and that the current round of talks would probably not solve the issue.

The GCF was agreed to at the COP 16 in Cancun, Mexico last year. It requires developed countries to provide 100 billion dollars to poorer countries by 2020 to help them cope with carbon emissions and adapt to climate change.

The United States has demanded that apart from developed countries, developing nations should also contribute to the fund. Another major issue is whether the private sector should be given direct access to the fund, as an equal partner with the other two main targets of the fund, mitigation and adaptation.

These requirements are not completely in line with the Copenhagen Accord and Cancun Agreements. Analysts said the debt crisis and sluggish economy may have further reduced the United States' willingness to help fund the developing nations' fight against climate change.

On the other side of the debate, delegates from developing countries which would benefit from the fund insist that the fund be finalized in Durban.

The Group of 77 (G77) and China, which support the GCF, said the fund is a "crucial element to the solution of global (climate change) problems."

The Alliance of Small Island States (AOSIS), which includes some of the world's lowest-lying and most vulnerable countries, said it is not satisfied with some of the principles in the draft document, but that it should be adopted "without delay."

The GCF also has the backing of the powerful 27-member European Union negotiating bloc, least-developed countries, and the Environmental Integrity Group made up of Mexico, South Korea and Switzerland.

The U.S. response, which has hampered efforts to kickstart the fund, has drawn criticism from some negotiating parties and NGOs. ActionAid International, an organization that fights global hunger and climate change, reacted with anger at the possibility of failure.

"It is scandalous that the USA is attempting to railroad negotiators from putting into action a climate cash plan agreed in Cancun last year," Henry Malumo, the organization's Africa policy and campaign manager, was quoted as saying.