The government in South Africa, which is hosting a United Nations climate change conference, has said there has been agreement on a number of key issues.

However, the European Union and some smaller nations say a draft text drawn up by the host country does not refer to a legally-binding deal that will curb emissions before 2020.

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 yesterday, dragged on throughout today 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 today.

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% 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 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.