The Union of South American Nations seeks to make a deep impact in Latin America without ruffling feathers in two competing organizations, the regional bloc's secretary-general, Nestor Kirchner, said.

The former Argentine president, husband of incumbent Cristina Fernandez de Kirchner, named Mercosur trade bloc and the Andean Community as organizations he would be wary of bringing into conflict with the new group.

Kirchner made no mention in this context of the Organization of American States, the Washington-based regional body that is widely seen as the target for Unasur's emergence as a potential counterpoint to the OAS.

Unasur is made up of Argentina, Bolivia, Brazil, Chile, Colombia, Ecuador, Guyana, Paraguay, Peru, Suriname, Uruguay and Venezuela.

OAS, the world's oldest regional organization and offspring of the 1889-90 First International Conference of American States in Washington, is made up of 35 states including Caribbean nations, Canada and the United States.

Mercosur, founded as a trade bloc in 1991, includes Argentina, Brazil, Paraguay and Uruguay as full members, Bolivia, Chile, Colombia, Ecuador and Peru as associates and Venezuela as a full member awaiting confirmation.

The Andean Community, founded in 1969 as a trade bloc, currently has Bolivia, Colombia, Ecuador and Peru as members. Founding member Chile withdrew in 1976, and Venezuela joined in 1973 but pulled out in 2006.

After Unasur's formation in 2008 leaders and officials made clear they expect the new bloc to replace both the Community of Andean Nations and Mercosur to become a supranational regional union.

An underlying though usually unstated goal of Unasur, analysts said, remains dislodging of OAS from South America.

Plans for a Unasur headquarters, to be set up in Ecuador, and a regional parliament based in Bolivia remain under a prolonged period of implementation. Unasur's constitution and charter still has to be approved by the legislatures of several member countries to become effective.

Although the headquarters idea hasn't been shelved, it now seems likely a secretariat will be based in Buenos Aires.

This is because Kirchner, elected for two years in May, is still politically active in Argentina though no longer has an executive post in his wife's presidency.

Kirchner, 60, recently underwent emergency surgery to remove a blockage in his carotid artery.

Unasur officials said the organization was considering the appointment of independent nominees to work for Unasur rather than assigning the tasks to government ministers in the country that holds the group's presidency.

Currently Unasur's presidency is held by Ecuadorian President Rafael Correa. Kirchner and Correa met this week to discuss what officials described as matters of priority for taking Unasur forward.

Before formally starting his work with the Ecuadorian Unasur team, Kirchner underlined the regional group must avoid any potential conflict with the Andean Pact or Mercosur.