Prime Minister Stephen Harper and Indian Prime Minister Manmohan Singh hold a meeting at the Commonwealth heads of government summit in Port-of-Spain, Trinidad, on Saturday. (Chris Wattie/Reuters)Commonwealth nations, including Canada, called for a legally binding international deal on climate change and backed the idea for a fund to help poorer countries cope with the effects of a warming planet.

The 53 nations — many of which are smaller island states prone to rising sea levels and other effects of climate change — said Saturday a climate deal should be adopted no later than next year and that a special fund should begin in 2010 and grow to $10 billion US annually by 2012.

"Climate change is the predominant global challenge," the Commonwealth leaders said in a declaration Saturday. "For some of us, it is an existential threat."

The document called for a "legally binding" agreement.

"I look forward to seeing a comprehensive agreement in Copenhagen where we'll actually get on with actually reducing emissions as opposed to setting abstract targets," said Prime Minister Stephen Harper, who is attending the three-day Commonwealth meeting in the twin-island Caribbean nation of Trinidad and Tobago.

Harper agreed only two days ago to attend next month's UN meeting after U.S. and Chinese leaders agreed to go, and was urged on Friday by UN Secretary General Ban Ki-moon to set ambitious greenhouse gas emissions targets as soon as possible.

Ban and Danish Prime Minister Lars Loekke Rasmussen made rare appearances at the Commonwealth meeting on Saturday to help drive the climate discussion.

"My message to all the leaders is quite simple: stay focused, stay committed and come to Copenhagen and seal a deal in Copenhagen," Ban said.

It seems to be having an effect on Harper, the CBC's Terry Milewski reported, adding that the prime minister has stopped saying a deal is unlikely but stressing that it will be difficult.

"I think the expectation is at this point that we will reach a meaningful political framework agreement in Copenhagen that can lead in the very near future to a binding international legal agreement," Harper said. "But that will involve mitigation actions from all major emitters, combined with arrangements on financing and technology that will make those feasible. So I think that's all possible, but I'm not going to suggest to you that it's all easy. There's a great deal of work to be done."

The meeting of the Commonwealth, made up mostly of former British colonies, attracted an unusual level of attention this year because of climate change. The gathering, held every two years, brought together some of the key countries in the global debate, including India, Canada and Australia, amid debate over cutting carbon emissions and the economic effects of those cuts.

Indian Prime Minister Manmohan Singh said Friday that his country is willing to sign an ambitious global target. But he set no specific figures and insisted it be accompanied by "equitable burden sharing."

Australian Prime Minister Kevin Rudd told reporters that "progress is being made. You see as each day passes a large number of states come forward with their own national commitments."

With files from The Associated Press