The new bloc would be an alternative to the Organisation of American States (OAS), the main forum for regional affairs in the past 50 years.
Mexico has been hosting a regional summit in the beach resort of Cancun.
The OAS has been dogged by rifts between some members and the US over economic policy and trade, and criticised for promoting US interests.
The proposed new grouping was one of the main issues on the agenda of the two-day summit, which ended on Tuesday.
It "must as a priority push for regional integration... and promote the regional agenda in global meetings", Mexican President Felipe Calderon told the summit, which includes leaders and representatives from 32 countries.
It's very important that we don't try to replace the OAS. The OAS is a permanent organisation that has its own functions
Chilean President-elect Sebastian Pinera
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