Negotiations at the UN climate summit have been suspended after developing countries withdrew their co-operation.
Delegations were angry at what they saw as moves by the Danish host government to sideline talks on more emission cuts under the Kyoto Protocol.
As news spread around the conference centre, activists chanted "We stand with Africa - Kyoto targets now".
But talks between the parties were expected to resume in the afternoon and informal discussions continue.
The countries that have suspended co-operation are those which make up the G77-China bloc of 130 nations. These range from wealthy countries such as South Korea, to some of the poorest states in the world.
The G77-China bloc speaks for developing countries in the climate change negotiation process.
Blocs representing poor countries vulnerable to climate change have been adamant that rich nations must commit to emission cuts beyond 2012 under the Kyoto Protocol.
But the EU and the developed world in general has promoted the idea of an entirely new agreement, replacing the protocol.
Developing countries fear they would lose many of the gains they made when the Kyoto agreement was signed in 1997.
They point out that the Kyoto Protocol is the only international legally binding instrument that has curbed carbon emissions, and also that it contains functioning mechanisms for bringing development benefits to poor countries such as money for investment in clean energy projects.
Previously during this meeting - formally called the Conference of the Parties (COP) 15 - developing countries have accused the Danish chairs of ignoring their concerns.
G77-China chief negotiator Lumumba Di-Aping explained why the bloc had taken the decision to withdraw its co-operation.
"It has become clear that the Danish presidency - in the most undemocratic fashion - is advancing the interests of the developed countries at the expense of the balance of obligations between developed and developing countries," he told BBC Radio 4's The World at One programme.
"The mistake they are doing now has reached levels that cannot be acceptable from a president who is supposed to be acting and shepherding the process on behalf of all parties."
Last week, the Pacific island nation of Tuvalu forced a suspension after insisting that proposals to amend the UN climate convention and Kyoto Protocol be debated in full.
At a news conference earlier in the day, UK Climate Secretary Ed Miliband said that for the developed world to commit to further cuts under the Kyoto Protocol would be "irresponsible for the climate".
He said it would leave some of the world's biggest emitters without targets for cutting emissions.
Many developing countries have been arguing for a "twin track" approach, whereby countries with existing targets under the Kyoto Protocol (all developed nations except the US) stay under that umbrella, with the US and major developing economies making their carbon pledges under a new protocol.
Kim Carstensen, director of the global climate initiative with environment group WWF, said that much more movement was needed on the Kyoto Protocol negotiations here.
"The point is being made very loudly that African countries and the wider G77 bloc will not accept non-action on the Kyoto Protocol, and they're really afraid that a deal has been stitched up behind their backs," he told BBC News.
While understanding the G77 position, he said the suspension could affect progress towards a deal.
"We're losing time, and that's a serious matter; because for every minute we lose on one issue, the chances of getting to the bottom of the next issue diminish."
The Danish government has yet to make any formal response; but Australian Climate Minister Penny Wong described the suspension as "regrettable".
Yvo de Boer, executive secretary of the UN climate change convention, predicted that the negotiations would get back on track in the early afternoon.
"The vast majority of countries here want to see the continuation of the Kyoto Protocol," he said.
"I'm not aware that any countries are trying to block anything."
An African bloc walkout during prepatory talks in Barcelona in November proved unpopular with other developing countries, in particular some small island nations.
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