In a speech after Friday's ceremony, which was also attended by Rafael Correa, Ecuador's president, Chavez defended his plan to extend a vast gas pipeline across South America.
He said: "Some say that I'm mad, that this gas pipeline is madness. Whoever says that should go and see the pipelines in Europe that run from Siberia to Portugal."
Venezuela and Colombia are to study the possibility of extending the pipeline to Panama "and then to the rest of Central America," Ramirez said.
Chavez said such an extension would make Central American countries less dependent on outside sources such as the United States and reduce pressure for free-market policies.
Venezuelan officials said the pipeline will flow from Colombia to Venezuela until 2011, and then reverse course to carry gas from Venezuela's vast, largely untapped reserves to Colombia.
Chavez and Uribe agreed to build the pipeline between Colombia's La Guajira gas fields and Venezuela's Paraguana refining complex in 2005.
Paraguna is Venezuela's largest refinery and requires large amounts of natural gas for petroleum refining.
In a separate development, Uribe announced that Colombia would formally request to join a regional development bank backed by Chavez that is to launch next month in Caracas, Venezuela's capital.
Uribe, who is Washington's closest ally in the region, said: "Our entrance into the Bank of the South is not a rejection of the World Bank or the Inter-American bank but an expression of solidarity and loyalty with the South American brotherhood."
Chavez has pushed the bank as a counterweight to US influence, especially the US-dominated World Bank, and as a path to economic independence for the region.