The Quito meeting is looking at aid but also longer-term help
South American leaders are holding a summit in the Ecuadorean capital, Quito, to discuss how to help Haiti recover from last month's earthquake.
Haitian President Rene Preval is there to set out his country's needs and priorities to fellow leaders.
It is the first visit to Ecuador for Colombian President Alvaro Uribe since 2008, when his forces attacked a rebel camp over the Ecuadorean border.
The raid provoked a diplomatic rift between the two nations.
Ecuador and Colombia have since resumed low-level relations but tensions remain.
Venezuela's president, Hugo Chavez, who has been vocal in his criticism of the US-led relief efforts, meanwhile cancelled his visit at the last minute, citing domestic issues.
Venezuela last month forgave Haiti's $295m oil-related debt.
Tuesday's meeting is of the regional body, the Union of South American Nations (Unasur).
The crisis in Haiti is so important that it may overshadow regional differences, Michael Shifter of the Inter-American Dialogue in Washington told Reuters.
"Haiti could be a unifying issue for the continent. Distrust won't disappear but this meeting might be a welcome respite".
Ecuadorean President Rafael Correa, who called the meeting, said the aim was to boost Haiti's institutions and make it less reliant on outside help.
"Without government and institutions, the country will not be able to move forward, except as a colony, and we're not going to allow that," Mr Correa said.
South American nations sent doctors, food and aid supplies to Haiti after the 12 January earthquake that left some 200,000 people dead and more than a million homeless.
Among nations planning financial help Brazil, which heads a UN peacekeeping mission in Haiti, is drawing up a $200m package to help reconstruction efforts.