The European Union warned on Saturday that a UN summit in Madrid must send a strong signal that countries are ready to do more to cut emissions, as fears grew that international efforts to fight climate change were slipping into reverse.
The two-week round of annual climate negotiations had been due to conclude on Friday, but dragged on into the weekend as delegates failed to resolve multiple disputes over implementing a climate accord forged in Paris four years ago.
Krista Mikkonen, Finland's environment minister, speaking on behalf of the EU, told the latest session at the talks that it would be "impossible to leave" without agreeing a "strong message" on the need to redouble pledges to cut emissions next year, when the Paris deal enters a crucial implementation phase.
"This is something that the outside expects from us and we need to hear their calls," Mikkonen said.
Countries including Nepal, Switzerland, Uruguay and the Marshall Islands echoed the call from the EU for more ambition.
Observers say that the latest draft statements drawn up by Chile, which is presiding over the summit, for consideration by delegates lack the kind of strong commitments needed to inject fresh momentum into the faltering Paris process.
"We are in the final (stage) of these negotiations and what we see thus far is that this text is completely unacceptable and it would be a betrayal of people around the world suffering from the impacts and those that are calling for action," Jennifer Morgan, executive director of Greenpeace International, told reporters.
"The Chilean presidency had one job, to protect the integrity of the Paris Agreement and not allow it to be torn apart by cynicism and greed and right now it is failing," Morgan said, expressing mounting outrage among climate campaigners.
Morgan named the United States, which has begun the process of leaving the Paris Agreement, Japan, and Brazil as among the biggest obstacles to meaningful action.
With global emissions hitting a record high last year, countries pushing for stronger climate action say that big polluters must agree to submit more ambitious pledges next year to give the accord a fighting chance of success.
Bhutan's Sonam Phuntsho Wangdi, who chairs a bloc of Least Developed Countries, told the session he could not "face our peoples back at home" without a stronger outcome to protect the world from the worst impacts of climate change.