Several developing countries have refused to participate in talks at the UN climate summit in Copenhagen, demanding that rich countries discuss much deeper cuts in their greenhouse gas emissions.
African delegates returned to the working group meetings on Monday after a boycott lasting several hours.
The impasse as the conference entered its second week is likely to have added to growing pessimism that a meaningful deal will have been secured when more than 100 world leaders to arrive in the Danish capital in the coming days.
Zia Hoque Mukta, a delegate from Bangladesh, said developing countries had demanded that Connie Hedegaard, the conference president, bring the industrial nations' emissions targets to the top of the agenda before talks could resume.
"Trust is a major issue. We have lost faith [in Hedegaard]," Mukta said.
Poorer countries, supported by China, say Hedegaard had raised suspicions that the conference was likely to kill the 1997 Kyoto Protocol, which limited carbon emissions by wealthy countries and imposed penalties for failing to meet those targets.
Developing countries want to extend that treaty because it commits rich nations to emissions cuts but does not make any legally binding requirements on developing countries.
"We are seeing the death of the Kyoto Protocol," Djemouai Kamel of Algeria, the head of the 50-nation Africa group, said.
He said that African nations were demanding a special plenary session to discuss extending Kyoto.
Al Jazeera's Tania Page, reporting from Copenhagen, said the walkout marked a sign of "serious turbulence" at the summit.
"It is a sign that patience is wearing thin here in Copenhagen, both inside and outside the summit venue," she said.
"This was a tactic to grab attention, and you can certainly say that it has worked. What these countries are concerned about is that these talks are dissolving among a lot of distractions. They want to make the Kyoto Protocol the priority.
"They're saying, why not ensure that those wealthy countries commit to further cuts and that the Kyoto Protocol is extended?"
"I think we'll end up with something at the end of the week that is not going to be as strong as many of those developing countries would [want]."
Yvo de Boer, the UN's climate chief, said there was widespread sympathy for Africa's concerns.
"I think this is not just an African concern," he told a news conference. "The vast majority of countries here want to see an extension of Kyoto."
An African delegate, speaking on condition of anonymity, said developing countries had decided to block the negotiations at a meeting hours before the conference was to resume after a break on Sunday.
He said applause broke out every time China, India or another country supported the proposal to stall the talks.
"I don't think the talks are falling apart, but we're losing time"
Kim Carstensen, WWF environmental group
Kim Carstensen of the WWF environmental group said that the developing countries were "making a point" before world leaders, including Barack Obama, the US president, arrived for the closing days of the conference.
"I don't think the talks are falling apart, but we're losing time," Cartensen said.
The office of Gordon Brown, the British prime minister, said he would arrive in Copenhagen on Tuesday, two days earlier than previously planned, in an attempt to inject momentum into the climate talks.
"His view is that these negotiations can't wait until the last minute. He believes that we have learnt the lessons from the G20, that it takes leadership to get involved and try to pull together what is required as soon as possible," Simon Lewis, Brown's spokesman, said.