BOGOTA – The smaller of Colombia’s two main guerrilla groups says the United States is spying on neighboring, leftist-led Venezuela from a Colombian base on the border.

U.S. military personnel have established an “underground base” at a Colombian army battalion headquarters in the northeastern province of Arauca, the National Liberation Army, or ELN, said in a statement posted on its Web site.

The alleged U.S. listening post is part of a conspiracy to “try to overthrow (Venezuelan) President Hugo Chavez,” the rebel group said.

The ELN said President Alvaro Uribe’s government has allowed more than 200 U.S. military personnel and contractors to operate from several bases in Arauca, center of Colombia’s oil industry.

“President Uribe not only paramilitarized the public administration and narcotized the Arauca economy, but he also handed over the territory for construction of gringo bases,” the rebel communique said.

Rebel chiefs also mentioned the accord Bogota recently signed with Washington – source of $500 million a year in military aid to Colombia – promising U.S. forces access to at least seven Colombian bases.

The bases pact has driven Colombian-Venezuelan relations to their lowest point in years and is a source of concern even to U.S. allies such as Brazil and Chile.

The statement also touts the ELN’s success last month in rescuing a high-ranking rebel as he was being transported from one prison to another.

With roughly 5,000 fighters, the ELN is about half the size of the Revolutionary Armed Forces of Colombia, known as the FARC. EFE