A major split between developing countries emerged on the third morning of UN climate talks here.Small island states and poor African nations vulnerable to climate impacts laid out demands for a legally-binding deal tougher than the Kyoto Protocol.
This was opposed by richer developing states such as China, which fear tougher action would curb their growth.
Tuvalu demanded - and got - a suspension of negotiations until the issue could be resolved.
The split within the developing country bloc is highly unusual, as it tends to speak with a united voice.
Tuvalu's negotiator Ian Fry made clear that his country could accept nothing less than full discussion of its proposal for a new legal protocol, which was submitted to the UN climate convention six months ago.
"My prime minister and many other heads of state have the clear intention of coming to Copenhagen to sign on to a legally binding deal," Mr Fry said.
"Tuvalu is one of the most vulnerable countries in the world to climate change, and our future rests on the outcome of this meeting."
The call was backed by other members of the Association of Small Island States (AOSIS), including the Cook Islands, Barbados and Fiji, and by some poor African countries including Sierra Leone, Senegal and Cape Verde.
Several re-iterated the demand of small island developing states that the rise in the global average temperature be limited to 1.5C, and greenhouse gas concentrations stabilised at 350 parts per million (ppm) rather than the 450ppm favoured by developed countries and some major developing nations.
Developing split
Fast-growing economies such as China, India and South Africa oppose the lower target of 350ppm because they feel that meeting it would retard economic development.
Here, they also opposed Tuvalu's call for a new legally-binding protocol to run alongside the existing Kyoto Protocol, arguing that the existing convention and Kyoto agreement are tough enough.
"The main task of this (conference) is to adapt an agreed outcome from the Bali Action Plan [agreed in 2007] and we should very much focus on that," said China's lead negotiator Su Wei.
"We have a very vaild system to combat climate change."
But the existing agreement is not tough enough for the smaller, more vulnerable members with more to lose from rising sea levels and less to lose in terms of the economic constraints of a tough treaty.
Mr Fry called for the Conference of the Parties - the official name for the full gatherings here of all countries - to be suspended if its proposal for full-scale discussions on the issue of a tough new protocol was not accepted.
Chairwoman Connie Hedegaard had to agree, moving on to other items to allow time for discussions behind the scenes.
During the same session, China - and other countries - re-iterated calls for industrialised nations to pledge bigger cuts in their greenhouse gas emissions.
But that has been a familiar call here; the rift between members of the formerly solid developing country bloc is a much less common happening, and may indicate that hopes held out by some countries of signing only a political commitment here may not be enough to placate the poorest and most vulnerable nations.
China has protested an incident which prevented a top diplomat from entering the vast Bella Center where the conference is underway. The director-general of China's climate change negotiation team told the meeting he is "extremely unhappy" that a Chinese minister was barred from entry on three consecutive days.
Su Wei said the unnamed minister has been trying to enter since Monday but failed despite having two security badges made out. Both badges were confiscated by security guards on Wednesday morning.
