A major split among developing countries has emerged on the third day of the United Nations climate conference in Copenhagen over how strict a new treaty should be.
Some members of the G-77 group of developing countries want a legally-binding deal tougher than the Kyoto Protocol. This is opposed by China and India, which fear economic damage from a tougher treaty.
Tuvalu demanded - and got - a suspension of negotiations until the issue could be resolved.
The call was backed by other members of the Association of Small Island States, including the Cook Islands, Barbados and Fiji, and by some poor African countries including Sierra Leone, Senegal and Cape Verde.
The BBC reports the split within the bloc is highly unusual, as it tends to speak with a united voice.
Any agreement made at Copenhagen is intended to supplant the 1997 Kyoto Protocol on climate change, the first phase of which expires in 2012.