The UN climate negotiations in South Africa will be "tough", with the big question focusing on the future of the Kyoto Protocol, the foreign minister said Friday after preparatory talks.

"It is going to be a tough COP (Conference of Parties) because it is a COP that can't avoid the political issues that were not thoroughly discussed in Cancun," Maite Nkoana-Mashabane told journalists, referring to a big meeting of the UN Framework Convention on Climate Change (UNFCCC) last December.

"We no longer have time to postpone the key issue, particularly of the second commitment period" of Kyoto, she said. "It has to be discussed in Durban."

Nkoana-Mashabane hosted two days of ministerial consultations attended by more than 40 countries which she said had seen opinion coalesce in favour of fresh Kyoto commitments after the current set of carbon curbs expires at end 2012.

"The majority of party members here were saying Kyoto is very, very important because this is the only instrument we have in the UNFCCC process that is legally binding."

Arduously negotiated, the Kyoto Protocol requires rich countries that have ratified it to sign on to binding goals in curbing greenhouse-gas emissions.

As a result, its critics say it is ineffective because it does not include the world's two biggest carbon emissions, China, which as a developing economy does not have carbon targets, and United States, which boycotted the accord in 2001.

But Kyoto's supporters say the protocol is a cornerstone for attacking climate change because of its legal teeth and its distinction between rich and poor.

The European Union (EU) is one such defender, but is cautious about signing up to a second commitment period without ambitious promises from the major emitters in a wider UNFCCC negotiation arena.

"The majority of the countries that were represented here ... are all saying that one of the key outcomes for Durban is that we commit on the second commitment of Kyoto," Nkoana-Mashabane said.

"There are a few countries who are still putting conditions to say 'if A happens or B happens, they think they will sign on', but they are not too many. So, therefore, again the general thrust of the outcome of this meeting was very positive."

Earlier talks to thrash out a planned $100-billion-a-year Green Climate Fund, established in Cancun in December, saw the United States and Saudi Arabia withdraw their support for the overall design supported by other countries, a London-based NGO, the International Institute for Environment and Development (IIED), said Thursday.

UNFCCC Executive Secretary Christiana Figueres said governments who sat on the fund's committee had decided to forward an "operating instrument" document to Durban.

"I'm actually confident that once that instrument is seen at the top... that it will be recognised as what it is, which is a very, very balanced document that seeks to begin to move forward a fund that has never been seen before," she added.

Nkoana-Mashabane said activation of the fund, meant to help developing countries to tackle climate change, was vital.

"Developing countries demand a prompt start for the fund through its early and initial capitalisation."

The EU said the ministerial meeting had a "good atmosphere (but) could not hide the fact that the world is waiting for the US and the emerging economies to commit".

"A second commitment period of the Kyoto Protocol with the EU and other ambitious developed economies would cover only 15 percent of the global emissions," EU Climate Commissioner Connie Hedegaard noted in a statement.

"This is clearly not good enough. We need commitments also from the other big emitters."

The Durban conference takes place from November 28 to December 9.