Caracas, Venezuela ? The U.S. ambassador to Venezuela said Thursday that Colombian guerrillas have an “active presence” in the country and accused President Hugo Chavez of being uncooperative in counterterrorism efforts.

Ambassador William Brownfield said the United States is concerned about the presence in Venezuela of the Revolutionary Armed Forces of Colombia, or FARC, and the National Liberation Army, or ELN, both of which the U.S. considers terrorist organizations.

Colombian rebels have for decades been known to slip across the border and, at times, set up camps in Venezuelan territory.

Brownfield said “the active presence of some organizations in Venezuela, such as the FARC and ELN” was a factor in a U.S. decision to classify Venezuela as uncooperative on the issue of terrorism, along with its close ties to Iran and Cuba.