A Canadian pullout of the Kyoto Protocol would badly damage a UN climate process already weakened by divisions, negotiators and NGOs said Tuesday at talks in Durban, South Africa.

"For countries that are historically responsible for the problem to explicitly back out would undermine the process and the credibility of what we are trying to do," said Seyni Nafo, spokesman for the 54-nation Africa Group in the UN forum.

"How are we to going to ask India and China to do more when Canada is saying, 'OK, we're checking out of the Kyoto Protocol?"

On Monday, Environment Minister Peter Kent, speaking in Ottawa, said Canada "will not make a second commitment to Kyoto."

He refused to confirm or deny reports that his country had already decided to formally pull out of the pact.

Kent said Canada's goal was "a new international agreement, eventually binding, which would include all the major developed and developing emitters."

The UN Framework Convention on Climate Change (UNFCCC) gathers 194 countries under a process launched under the 1992 Rio Summit.

Tension at the annual talks, running in Durban until Decemer 9, is running high over the fate of Kyoto, the only global accord that specifies curbs in greenhouse gases.

Current pledges by rich countries under Kyoto expire at the end of 2012.

Several key nations beside Canada, including Japan and Russia, have said they will not renew their vows.

They say a second commitment period is senseless so long as emerging giants and the United States, which has refused to ratify the Protocol, are not bound by the treaty's constraints.

Even the European Union (EU), a consistent champion of the treaty, says its continued support is conditional.

But the bigger question is one of formal withdrawal.

If Canada did so, it would be the first country to abandon the agreement after ratifying it, an action that would carry a symbolic wallop.

Nafo and others at the Durban talks that got underway Monday emphasised that Canada has not yet withdrawn from the treaty.

"If I understand it correctly, there is some internal thinking on going on Canada's position on the KP," said the EU's chief negotiator, Artur Runge-Metzger.

"Of course if they would leave the Kyoto Protocol, that would be a sad thing."

Green groups reacted angrily to the prospect of a Canada pullout.

"If confirmed, it would be extremely disappointing," said Tasneem Essop, head of international climate strategy for WWF.

"It would have an impact on the Canadian government's ability to enter into these negotiations with credibility," she told AFP.

"Canada pulling out of the Kyoto Protocol would set an extremely bad precedent here at the talks. It can do nothing but further enhance the mistrust that already exists between rich and poor nations," said Ilana Solomon of ActionAid.

Japan repeated Tuesday that it would not renew its Kyoto vows, but said it had no intention of a formal withdrawal.

"We believe that there are good elements in the Kyoto Protocol," said Masahiko Horie, ambassador for global environment affairs.

Canada agreed under the Kyoto Protocol to reduce CO2 emissions to 6.0 percent below 1990 levels by 2012, but emissions have instead increased. Pulling out of Kyoto would allow Canada to avoid paying penalties for missing its targets.