Ministers fought to save U.N. climate talks from collapse on Saturday, searching to narrow differences between rich and poor nations over how quickly to fight global warming.

Ministerial negotiations in the South African port city of Durban were put off until Saturday afternoon but with many delegates due to head home there was a strong chance real decisions would be put off until next year.

That would be a major setback for host South Africa and raise the prospect that the Kyoto Protocol, the only global pact that enforces carbon cuts, could expire at the end of next year with no successor treaty in place.

It's a complete mess in there, but we are still trying to reach a deal, said one western delegate outside the building where ministers were trying to hammer out an accord.

Negotiators were arguing over the wording of a range of highly technical sections that make up the broad agreement, which covers a range of topics from greenhouse gas emissions targets to forestry accounting rules, green tech transfers and cash to help poor countries adapt to climate change.

Two weeks of talks between almost 200 states in the South African port of Durban were due to end on Friday. But island nations and developing states most affected by global warming rebelled over an initial draft accord.

They demanded a more ambitious text that could offer hope to low-lying countries under threat from the rising sea-levels and extreme weather linked to global warming.

The European Union backed the group, having sought to build a consensus around its roadmap for push all major polluters to accept legally binding cuts in their greenhouse gas emissions.

They're working. They're working hard. You have to give them time to work, said U.N. climate chief Christiana Figueres.

TICKETS HOME

However, as the talks dragged on, many delegates from poor nations were packing their bags, having booked flights home. That could leave the countries most vulnerable to climate change without a voice when the plenary session reconvenes.

Developing countries have very small delegations, 2-3 people... Many of us have already left, said Tosi Mpanu-Mpanu, chairman of the Africa Group. Many ministers are also gone from our group, so that creates a bit of a problem.

South African Foreign Minister Maite Nkoana-Mashabane has struggled to draft a document that can both advance the fight against climate change and secure a broad consensus.

Changes put forward on Saturday disappointed developing states and the European Union, who complained they contained no reference to how the fight against climate change would be paid for and set no date by when cuts to emissions must be decided.

The discussion document also deferred decisions on cutting emissions from international aviation and shipping to next year.

We're working very hard within those time constraints to get a successful outcome ... We are in the hands of the (South African) presidency as to the next steps, Britain's climate secretary Chris Huhne.

The European Union has tried to rally support for its plan to set a date of 2015 at the latest for a new climate deal that would impose binding cuts on the world's biggest emitters of heat-trapping gases. Any deal could then come into force up to five years later.

FRUSTRATION

But Washington says it will only pledge binding cuts if all major polluters make comparable commitments. China and India say it would be unfair to demand they make the same level of cuts as the developed world, which caused most of the pollution responsible for global warming.

Delegates in Durban have also been discussing a raft of other measures, whose fate would be unclear if the talks ended inconclusively.

They include measures to protect forests and another to bring to life the Green Climate Fund, designed to help poor nations tackle global warming.

U.N. reports released in the last month show time is running out to restrict global warming to safe limits, generally accepted as within a 2 degree Celsius rise in average global temperatures. A warming planet has already intensified droughts and floods, increased crop failures and sea levels could rise to levels that would submerge several small island nations.

Many of their delegates are frustrated that South Africa has failed to do enough to broker a deal that better protects the poor countries it pledged to help and failing to show the leadership needed to push through settlements.

They have let agreements slip through their fingers. If we do reach any outcome that advances the process, it will not be because of South Africa's leadership. It will be despite South Africa, said one envoy.

(Additional reporting by Barbara Lewis, Agnieszka Flak, Andrew Allan and Michael Szabo; editing by Jon Boyle)