Chavez said he would not permit Colombia's U.S.-backed government to establish an American military base in La Guajira, a region spanning northeastern Colombia and northwestern Venezuela.
The Venezuelan leader said if Colombia allows the base, his government will revive a decades-old territorial conflict and stake a claim to the entire region.
"We will not allow the Colombian government to give La Guajira to the empire," Chavez said, referring to the U.S. during a speech to a packed auditorium of uniformed soldiers. "Colombia is launching a threat of war at us."
He said Washington's top diplomat in Bogota, U.S. Ambassador William Brownfield, recently suggested that a U.S. military base in Ecuador could be moved to La Guajira.
Chavez urged his Colombian counterpart, Alvaro Uribe, to "think it over well" before making such a decision because Venezuela will do "whatever it takes" to ensure that a U.S. military base is not built on the peninsula in the Caribbean Sea.
Ecuadorean President Rafael Correa - a close Chavez ally - has repeatedly said that he will not renew a 10-year lease on the base in the Pacific port of Manta when it expires next year.
Manta is the United States' only military base in South America. Surveillance flights the U.S. runs from there are responsible for about 60 percent of drug interdiction in the eastern Pacific.
Diplomatic relations between Caracas and Bogota have been rocky for months. They worsened last week when Colombia unveiled documents allegedly showing that Chavez sought to arm and finance Colombian rebels. Chavez denies the claim.
Colombian officials say they found the documents in laptops recovered after a March 1 cross-border raid in Ecuador that killed rebel leader Raul Reyes and 24 other people.
International police agency Interpol is analyzing the documents and plans to present its findings on Thursday in Bogota.
"The Colombian government will surely announce tomorrow that the documents retrieved from Raul Reyes' computer are authentic and, therefore, Chavez supports terrorism," Chavez said.
Chavez - an outspoken critic of U.S. foreign policy in Latin America - said Washington is using Uribe as pawn in a plan aimed at portraying Venezuela as a backer of terrorism.
Chavez denies supporting the Revolutionary Armed Forces of Colombia, or FARC, saying he only seeks a peaceful end to the neighboring country's decades-long armed conflict.
The European Union joined the United States in listing the FARC - Latin America's largest rebel force with roughly 14,000 fighters - as a terrorist group in 2002, outlawing economic support for the guerrillas.
© Copyright 2008 The Associated Press