* Trinidad meeting last summit before U.N. climate talks
* U.N. chief, French and Danish presidents also attending
* International consensus sought for climate pact
* Commonwealth expected to admit Rwanda as new member
By Pascal Fletcher
PORT OF SPAIN, Nov 25 (Reuters) - Rich and poor states grouped in the Commonwealth and representing a quarter of the world's population hope to create critical momentum toward a global climate deal when they meet in the Caribbean this week.
Leaders of the 53-member Commonwealth, a group of mostly former British colonies, gather in Trinidad and Tobago from Friday in the last major international summit before high-level U.N. climate change talks due in Copenhagen on Dec. 7-18.
They have placed the climate issue at the top of their agenda in Port of Spain, along with measures to beat the global recession and democracy-building.
They will be joined in Trinidad by U.N. Secretary-General Ban Ki-moon, French President Nicolas Sarkozy and Danish President Lars Lokke Rasmussen, who want to use the Commonwealth gathering to cement an international consensus on cutting greenhouse gas emissions and limiting global warming.
Although most nations have given up hopes of agreeing to a binding legal treaty text in Copenhagen, the Commonwealth is viewed as an important microcosm in which to align such a consensus on a far-reaching climate pact.
"They want to clinch a deal, as much as possible ... at least try and build consensus and keep the smaller states on board," Victoria teVelde, director of the Commonwealth Policy Studies Unit, a University of London think tank, told Reuters.
The sought-after treaty to fight global warming, now expected to be adopted as a final text only next year, will replace the Kyoto Protocol that expires in 2012.
TeVelde said the leaders of the Commonwealth, which includes many small island states that fear rising sea levels caused by global warming could threaten their future existence, were expected to issue a firm and clear statement in favor of reducing global carbon pollution and how best to achieve this.
Trinidadian Prime Minister Patrick Manning had set aside the whole of Friday's agenda for discussion on climate change.
TeVelde said a clear stance by the Commonwealth, which includes five members of the G20 group, would send a "powerful message" for a climate deal ahead of the Copenhagen talks.
One intended recipient of this message would be the United States, the world's biggest per capita emitter of greenhouse gases, which has been accused of vacillating over setting clear new greenhouse gas emissions goals. China, the world's top carbon polluter, is watching the U.S. position closely.
A climate bill in the U.S. Senate has been making slow progress, although President Barack Obama's administration indicated this week it would bring an emissions cut target to the table in Copenhagen.
RWANDA TO JOIN
Commonwealth Secretary-General Kamalesh Sharma has said the Port of Spain summit will try to ensure the "voices of the poor and vulnerable" will be heard.
The Commonwealth, which was founded in 1931 mostly as a grouping of former British colonies, has widened its membership in recent decades, with Mozambique, a former Portuguese territory in Africa, joining in 1995. It aims to promote democracy and good governance and develop trade links among its members.
Commonwealth leaders in Port of Spain were expected to approve the admission of French-speaking Rwanda, whose President Paul Kagame has worked to bring his country into the English-speaking sphere in Africa after disagreements with France over events leading up to the 1994 Rwandan genocide.
But some human rights groups, such as the non-governmental Commonwealth Human Rights Initiative, have opposed Rwanda's admission on the grounds the country does not measure up to international standards for freedom and justice.
TeVelde said the Commonwealth, unlike some other international and regional bodies, had its own mechanisms, including sanctions like suspension, to try to ensure that members preserved acceptable levels of democracy.
In September, the Commonwealth suspended Fiji after the leaders of a 2006 coup failed to take steps to return the country to democracy.
The Port of Spain meeting was expected to also raise the possibility in the future of eventually readmitting Zimbabwe, which left the Commonwealth in 2003 after it was censured over a poll that re-elected President Robert Mugabe. Commonwealth observers had condemned his re-election as flawed. (Additional reporting by Adrian Croft and Linda Hutchinson-Jafar; Editing by Eric Beech) ((For Factbox on the Commonwealth, click on [ID:nN24312730])) ((For stories on climate change, click on [ID:nLL527527])) ((pascal.fletcher@thomsonreuters.com; +1 305 810 2688))