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".
Informal talks continue, and the UN climate convention head said the formal agenda should resume in the afternoon.
The countries which 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.