Foreign ministers from Unasur member nations met in the Ecuadorian capital Friday to put the finishing touches to the union's charter and treaty.
Unasur was formed in 2008 with the aim of integrating the Mercosur customs union and trade bloc and the Andean Community of Nations as part of a continuing process of South American integration. But the current grouping of 12 full members falls short of a full range of South and Central American nations that the organization set out to unite.
Mercosur's decision to go ahead with EU trade talks independent of Unasur sent a strong signal that Unasur was far from achieving its goal of becoming the predominant economic and political union in the region.
However, a combined population of 396 million makes the 12-member union an attractive port of call for countries or other regional groups seeking to expand ties with Latin America.
The current ministerial talks are aimed at choosing a successor to Nestor Kirchner, the former Argentine president who was elected the first secretary-general when the leaders met in Argentina in May 2010. Kirchner died last October.
Two candidates are vying for the post: Venezuela's Electricity Minister Ari Rodriguez, an energy expert, and Maria Emma Mejia, a former Colombian deputy foreign affairs minister, expert in international law and social inclusion.
Also Friday, the Constitutive Treaty signed in 2008 comes into force formalizing the birth of Unasur as a legal entity with headquarters in Mitad del Mundo, Ecuador.
Unasur members are: Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Guyana, Paraguay, Peru, Suriname, Venezuela and Uruguay.
Ecuadorian Foreign Affairs Ricardo Patino said that consolidation of Unasur will help political understanding and coordination among countries of the region and integration in areas such as infrastructure, health, education, social inclusion and energy development.
He said the member nations would seek agreements that went further than trade accords and led to eventual integration of the member states.
"What we are talking about is for agreements to go much further, not limited to trade issues but also to regional integration," said Patino, pointing to the benefits of an energy connectivity in the Andes area and integrated social security.
Within the short span of its existence Unasur has proved effective in defusing several regional conflicts including the confrontation between Venezuela and Colombia.
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