A draft global pact on climate change released Saturday boosted UN talks already deep into overtime, but negotiators worried that the late delivery could jeopardise a deal.
More than 120 ministers spread across half-a-dozen meetings were still receiving new text to review at 3:00am, hours after the 12-day conference under the UN Framework Convention on Climate Change (UNFCCC) was to have ended.
"The concern now is that time is extremely short," said EU Climate Commissioner Connie Hedegaard, who has spearheaded a drive to forge a legally binding climate agreement by 2015 covering the world's major carbon polluters.
"We still have a lot of text that is not there. It is very difficult to discuss one piece without the other, because in the end the things are interconnected," she told journalists.
For Mohamed Aslam, environment minister for the island state of the Maldives, "the biggest problem now actually is that we don't have time".
"If we can't reach a decision before the ministers leave, and we are still left with unresolved major issues, it will be difficult," he told AFP.
A loose coalition of nearly 90 African countries, least developed nations and small island states, along with Brazil and South Africa, have rallied behind the EU bid.
Besides the EU "roadmap", two other issues have dominated the talks, including a Green Climate Fund designed to disburse 100 billion dollars a year by 2020 to help poorer countries fight, and cope, with climate change.
The third is the fate of the Kyoto Protocol, which was hanging by a thread as the 194-nation conference began.
Key rich countries had announced their refusal to renew carbon-cutting pledges at the end of next year when the treaty's first round of cuts expires.
The EU -- which only accounts for 11 per cent of global emissions -- said it would take on new commitments, but only if major emitters, including the United States and China, would endorse the new climate pact.
As of late Friday, India and the United States showed scant enthusiasm for the scheme, while China was, in the words of one negotiator who asked not to be named, "running hot and cold".
Formal meetings were suspended until six the same morning, and a full plenary was slotted for 10:00am to gavel through any decisions made, though further delays were likely, many delegates said.
An outline deal prepared by host South Africa that circulated earlier Friday caused outrage among many poorer nations already coping with climate impacts ranging from more intense droughts to erratic rainfall to crippling heatwaves.
"I am disturbed to find that a legally binding protocol (Kyoto) ... negotiated just 14 years ago is now being junked in a cavalier manner," Indian Environment Minister Jayanthi Natarajan told fellow ministers behind closed doors, according to a transcript obtained by AFP.
But that first stab at consensus gave way hours later to a second document closer to the EU proposal, and received cautious praise.
"We feel much more convergence and that's a very good spirit," said Brazil's climate ambassador Luiz Alberto Figueiredo.
"The new text is a lot more to our liking," said Selwin Hart, a negotiator for Barbados and the 43-strong Association of Small Island States (AOSIS), pointing to a call for greater ambition in cutting CO2 emissions and a firm 2015 deadline for a global climate pact.
US negotiator Todd Stern refused to comment.
But wording on the new pact's legal form could hit a "sweet spot" between the EU's call for a "legally binding" deal and Washington's aversion to that term, said Tim Gore, a policy analyst with the NGO Oxfam.
More broadly, the second draft "means that we have moved away from the collapse scenario", he said.
But the problem of timing remained.
"This is probably close to what we can obtain as a balance," said French Environment Minister Nathalie Kosciusko-Morizet.
"That's the paradox of these talks -- we are starting to reach a balance, and it would really be a shame if, for organisational reasons, we don't succeed in going all the way."