The chairwoman of U.N. climate talks urged delegates to approve a compromise deal on fighting global warming in the interests of the planet, but a deal remained elusive as rich and poor states traded barbs over the limited scope of the package.

South African Foreign Minister Maite Nkoana-Mashabane said the four separate texts were not perfect but represented a good outcome after two weeks of sometimes fraught negotiations in the port city of Durban.

Let us agree to accept the Durban outcome package. I feel the four pieces of the package before us .... represent a comprehensive, balanced and credible set of outcomes for this conference, she said.

I think we all realise they are not perfect. But we should not let the perfect become the enemy of the good and the possible, she added.

The talks, which were due to end on Friday, dragged on throughout Saturday and looked set to continue into a second extra day, as visibly tired delegates argued over a deal.

The testy late night mood contrasted with an earlier mood of cautious optimism that had suggested agreement on the four separate accord in the package was possible on Saturday.

Sticking points included an extension of the Kyoto Protocol, the only global pact enforcing carbon cuts. The draft text says the second Kyoto phase should end in 2017, but that clashes with the EU's own binding goal to cut carbon emissions by 20 percent by 2020.

Venezuela's climate envoy lambasted the EU position she said anchors the lowest level of ambition and that actually promises us a second commitment period that is completely weak. Other envoys defended the EU bloc for enshrining its pledge in law.

Behind the haggling, the talks have boiled down to a tussle between the United States, which wants all polluters to be held to the same legal standard on emissions cuts, and China and India who want to ensure their fast growing economies are not shackled.

Among technical points holding up the other accords in the proposed package were arguments over complex government emissions permits and forestry accounting rules.

HOPES DASHED?

The spectre of a collapse in the talks hovered over the dragging negotiations. Failure would be a major setback for host South Africa and raise the prospect that the Kyoto Protocol could expire at the end of 2012 with no successor treaty in place.

Earlier, Brazil's climate envoy Luiz Alberto Figueiredo Machado had said he believed a deal would still be done, avoiding the postponement of decisions until next year.

We are agreeing. a protocol or another legal instrument. Everything is there, he said. Developing and EU states objected to the phrase legal framework in a previous draft, saying it was too vague, insisting instrument implied a more binding commitment.

That commitment would start by 2020, so as not to have a gap, he said. That date would meet a key EU demand.

Scientists warn, however, that time is running out to close the gap between current pledges on cutting greenhouse gases and avoiding a catastrophic rise in average global temperatures.

U.N. reports released in the last month warned delays on a global agreement to cut greenhouse gas emissions will make it harder to keep the average rise to within 2 Celsius over the next century.

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, who are holding out for more ambitious targets in emissions cuts.

(Reporting by Nina Chestney, Jon Herskovitz, Andrew Allan and Michael Szabo and Stian Reklev; editing by Jon Boyle)