Developing states most at risk from global warming rebelled against a proposed deal at U.N. climate talks, forcing host South Africa to draw up new draft documents to try to stop the talks collapsing.
Negotiations had yet to resume on Saturday after haggling in the South African port city of Durban continued into the early hours.
South African Foreign Minister Maite Nkoana-Mashabane at one point suspended the meeting because a coalition of island nations, developing states and the European Union complained the
text lacked ambition and another had to be drawn up.
There was a strong appeal from developing countries, saying the commitments in the proposed texts were not enough, both under the Kyoto Protocol and for other countries, Norway's Climate Change Minister Erik Solheim said.
The European Union has been rallying support to 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.
The crux of the dispute is how binding the legal wording in the final document will be. The initial draft spoke of a legal framework, which critics said committed parties to nothing.
A new draft changed the language to legal instrument, which implies a more binding commitment, and says a working group should draw up a regime of emissions curbs by 2015.
It also turns up pressure on countries to act more quickly to come up with plans for reducing domestic emissions.
The changes should appeal to poor states, small island nations and the European Union, but may be tough for major emitters, including the United States and India, to swallow, said Alden Meyer, director of strategy and policy at the Union of Concerned Scientists.
One of the crunch issues that has been left out is the date by which the new agreement will enter into force, which could still be as late as 2020 and making it no better than the previous text on this issue, said Tim Gore, climate change policy advisor for Oxfam.
The delegates are also expected to debate text on a raft of other measures, including one to protect forests and another to bring to life the Green Climate Fund, designed to help poor nations tackle global warming.
The EU strategy has been to forge a coalition of the willing to try to pressure the world's top carbon emitters -- China, the United States and India -- to sign up to binding cuts. None of the big three is bound by the Kyoto Protocol.
EU Climate Commissioner Connie Hedegaard said a small number of states had yet to sign up to the EU plan and there was little time remaining for a deal in Durban.
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.
Many envoys believe two weeks of highly complex climate talks, bringing together nearly 200 nations, will at best produce a weak political agreement, with states promising to start debate on a new regime of binding cuts in greenhouse gases.
At worst, the talks could collapse altogether, recalling the failure at the 2009 climate summit in Copenhagen.
Expectations Copenhagen would deliver a new global deal to follow on after a first set of Kyoto carbon cuts, which expires at the end of next year, were unreasonably high.
The U.N. negotiators regrouped in 2010 in Cancun, where a more modest programme of action and a set of voluntary pledges to curb carbon emissions were drawn up.
Scientists say those promises are not yet enough to limit global warming to the two degrees Celsius judged necessary to stave off the most devastating effects of climate change.
U.N. reports released in the last month show time is running out. 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.
The protracted talks frustrated delegates from small islands and African states, who joined a protest by green groups outside as they tried to enter the main negotiating room.
You need to save us, the islands can't sink. We have a right to live, you can't decide our destiny. We will have to be saved, Maldives climate negotiator Mohamed Aslam said.
(Additional reporting by Barbara Lewis, Agnieszka Flak, Andrew Allan and Stian Reklev)