"Together we go forward, divided we fall back," Argentine President Nestor Kirchner said.
Brazil's president, Luiz Inácio Lula da Silva, said South America's largest economy remains solidly behind "this great project."
Ecuador's President Rafael Correa moved his country closer to membership in the bloc by presenting a written pledge of respect for democracy, a requirement for joining the expanding group that currently includes Argentina, Brazil, Uruguay and Paraguay.
But the bloc took no major action on unified tariff reforms, despite calls by junior members Paraguay and Uruguay to ease policies they see favoring the big Mercosur nations (Brazil and Argentina). The group said the issue needs further study.
Venezuelan was represented by vice president Jorge Rodriguez since president Hugo Chavez was off to Russia allegedly for the purchase of four submarines. Rodriguez said Venezuela remains committed to becoming a full member of Mercosur.
He charged that those opposed to Venezuela's entry are "reactionary groups who only defend their interests," an apparent reference to Brazilian critics. A strong lobby of Brazilian legislators favor blocking Venezuela's bid, arguing it does not comply with democracy commitments.
Chavez has called the legislators a "pirate's parrot," suggesting they were voicing U.S. policies by criticizing Venezuela's decision last month not to renew the broadcast license of an opposition-aligned TV station.
Brazil's foreign minister has demanded a "goodwill gesture" from Venezuela before its Congress votes that country into the Mercosur trade bloc. But Chavez's government indicated again Friday it won't be extending an olive branch any time soon.
The presidential summit ended with the Mercosur six months rotating presidential chair been passed on to Uruguay's president Tabare Vazquez.
The following summit is scheduled to take place in Uruguay, next December.
Mercopress