South and Central American leaders have criticised developed countries for failing to eliminate barriers to free trade during a meeting in Guyana.
The Rio Group meeting on Saturday come as officials from the US, EU, Brazil and India hold talks on the stalled Doha Round of trade negotiations.
Bharrat Jagdeo, Guyana's president, said at the talk's opening session on Friday: "The slow pace of the Doha Round of trade negotiations within the World Trade Organisation is a striking demonstration of the indifference on the part of the developed world to the welfare of the developing world."
He called on Latin American countries to "seek ... to find common grounds from which we can fight for the interest of the poor and underprivileged of our countries".
"The experience thus far has shown that the more powerful states are concerned only with preserving their interests. Their triumph once again would be a calamity for developing countries such as ours," he said.
Jagdeo recommended that the Rio Group establish a quasi-cabinet with specific presidential responsibilities aimed at ensuring "optimal and sustained representation."
The Rio Group summit will discuss how the organisation could improve its performance and ensure that developing countries have a greater say in international organisations like the UN, the International Monetary Fund and World Bank.
Talks will also focus on combating poverty and improving health and education, based on a study conducted by the UN Economic Commission for Latin America and the Caribbean.
The group will also discuss the post-elections situation in Haiti, where several Rio Group members are participating in the UN Stabilisation Mission.
The Dominican Republic will take over the chairmanship of the Rio Group from Guyana at the end of the summit.
The Doha Round of talks on free trade has been stalled since last July.
Brazil and India say the talks should focus on agriculture, with safeguards for developing countries manufacturers.