Sleep-deprived COP26 negotiators on Saturday struggled to bridge deep divisions holding up a deal to deliver the emissions cuts and financial support needed to avert the accelerating disaster of climate change.

A new draft text, released deep into overtime by the Glasgow summit's UK presidency, urged nations to accelerate efforts to phase-out of unfiltered coal and "inefficient" fossil fuel subsidies.

Large emitters such as China, Saudi Arabia and Russia had tried to remove the mention of polluting fuels, according to delegates.

But after resistance from rich nations led by the United States and European Union, the draft text omitted any reference to a specific finance facility for "loss and damage" -- the mounting cost of global warming so far -- which has been a key demand of poorer nations.

The text noted "with deep regret" that wealthy nations had also failed to stump up a separate annual sum of $100 billion they promised over a decade ago, but said only that it would come by 2023.

Greenpeace International chief Jennifer Morgan told AFP that the language on fossil fuels "is far from what is needed but sends a signal- I dare countries to take that out of the text right now".

"The US has to support the most vulnerable on the issue of loss and damage. They cannot avoid this issue any longer. Nor can the European Union," she added.

"I would call on President (Joe) Biden to do what's right, and support the most vulnerable in helping them deal with their losses."

The US and EU delegations did not immediately respond to requests for a comment.

'Bullied'

Saleemul Huq, director of the ICCCAD climate NGO, said the British COP26 presidency had been "bullied" overnight into rejecting specific loss and damage funding.

"The UK's words to the vulnerable countries have been proven to be totally unreliable," he said.

One observer party to discussions told AFP they expected developing nations to "push back and try to turn the dialogue into something that is not endless blah, blah, blah".

Delegates from nearly 200 countries are in Glasgow to try to hammer out how to implement the 2015 Paris Agreement goals to limit temperature rises to 1.5-2 degrees Celsius.

The third round of revisions since Wednesday came after frenetic haggling that stretched overnight past the summit's scheduled conclusion on Friday evening.

Countries already battered by climate disasters such as record-breaking drought, flooding and storms are demanding they be compensated separately for loss and damage, and have made it a red line issue.

However, a proposal to include the creation of a dedicated facility to administer financial support was quashed by historical emitters, delegates said.

In its place was a line offering "dialogue to discuss the arrangements for the funding of activities" on loss and damage.

Amadou Sebory Toure, head of the G77+China negotiating bloc, told AFP the proposal was "put forward by the entire developing world, representing six of every seven people on Earth".

He said separate finance was needed "to effectively respond to our needs to address the loss and damage being inflicted on our peoples, our communities, our economies, by the impacts of climate change".

Alden Meyer, senior associate at climate policy think tank E3G, said loss and damage talks were a "cliffhanger moment" that could jeopardise the UK's goal of wrapping the summit up later Saturday.

Developing nations say it is unfair for the summit to produce an unbalanced agreement heavily weighted toward "mitigation" -- how economies can ditch fossil fuels by 2050.

They want specific instruction on how they can meet the bill of decarbonising while also adapting to the natural disasters supercharged by global warming.

Before the Friday night deadline came and went, hundreds of indigenous and other protesters marched through the summit venue demanding the rich world honour its promises.

Pledges insufficient

The summit began with a bang as world leaders came armed with a string of headline announcements, from a commitment to slash methane emissions to a plan to save rainforests.

Negotiations received a further boost on Wednesday when the United States and China -- the two largest emitters -- unveiled a joint climate action plan, although it was light on detail.

But current plans to cut national emissions, all told, would lead to 2.7C of heating, according to the UN, far in excess of the Paris target.

The latest draft text requested countries to come back next year with updated climate pledges.