Chavez said Venezuela could end up going to war with Colombia as tensions between them rise, and he warned that if a conflict broke out "it could extend throughout the whole continent."
"The best way to avoid war is preparing for it," Chavez told military officers during his weekly television and radio program. Venezuela's socialist leader has also cited a recent deal between Bogota and Washington giving U.S. troops greater access to military bases as a threat to regional stability.
The government of Colombian President Alvaro rejected what it called "threats of war from Venezuela's government," saying it would protest Chavez's comments to the Organization of American States and the U.N. Security Council.
"Colombia never has, and never will, make an act of war," said government spokesman Cesar Mauricio Velasquez. He did not elaborate on Colombia's plans to bring the issue to the OAS and the United Nations.
Colombian and U.S. officials have repeatedly said Venezuela shouldn't be concerned about the base deal since it is aimed exclusively at boosting the fight against drug traffickers and insurgents in Colombia, which is a major cocaine producer struggling with a decades-old internal conflict.
Tensions along the Venezuela-Colombia border have been exacerbated in recent weeks by a series of shootings and slayings.
Four men on motorcycles shot and killed two Venezuelan National Guard troops at a checkpoint near the border in Venezuela's western Tachira state last week, prompting Chavez's government to temporarily close some border crossings.
And last month, Venezuelan authorities arrested at least 10 people in Tachira alleging involvement in paramilitary groups. The bullet-ridden bodies of 11 men, nine of them Colombians, were also found last month in Tachira after being abducted from a soccer field.
The violence prompted Venezuela to send 15,000 soldiers to the border with Colombia on Thursday. Officials said the buildup was necessary to increase security along the border.
Elsa Cardoso, a professor of international relations at the Central University of Venezuela, suggested that Chavez's heated rhetoric - coupled with the recent military deployments - are aimed at turning the public's attention away from pressing domestic problems ranging from rampant crime to electricity and water rationing.
"He's sending up a smoke screen, a distraction," she said.
Colombian rebels have often used Venezuela's border region as a haven to resupply and treat their wounded in recent years, creating friction with Colombia's U.S.-allied government.
Chavez - a former army paratrooper who during more than a decade in power has repeatedly accused Washington of seeking to topple him to seize Venezuela's oil reserves - warned President Barack Obama of using his alliance with Uribe to mount an offensive against Venezuela.
"The empire is more threatening than ever," Chavez said, referring to the U.S. government. "Don't make a mistake, Mr. Obama, by ordering an attack against Venezuela by way of Colombia."
Venezuelan opposition leader Julio Borges urged Chavez to hold talks with Colombian officials to ease the tensions.
"Working together is only way to efficiently confront this problem, to finally end the permanent threat from illegal groups such as paramilitaries and guerrillas," Borges said.
Associated Press writer Vivian Sequera in Bogota, Colombia, contributed to this report.