CARACAS, Venezuela (AP) — Venezuela’s defense minister on Friday warned Colombia against provoking a conflict after President Hugo Chávez severed ties with the nation and placed his military on alert.

Speaking on state television, Defense Minister Carlos Mata promised “a strong response” if foreign forces crossed into Venezuelan territory.

Mr. Chávez broke off all diplomatic relations with Colombia on Thursday, accusing it of fabricating evidence of Colombian rebel bases inside Venezuela.

At a meeting of the Organization of American States in Washington on Thursday, the Colombian ambassador, Luis Alfonso Hoyos, presented photographs, videos, witness testimony and maps of what he said were rebel camps in Venezuela, and he challenged Venezuela to let independent observers visit them.

Mr. Chávez suggested that Colombia’s president, Álvaro Uribe, who leaves office next month, could be trying to provoke a war, and that the photographs were fake. He insisted Venezuela did everything possible to prevent Colombian rebels from crossing into Venezuelan territory.

In Washington, the State Department spokesman, P. J. Crowley called the dispute unfortunate and said it was a “petulant response by Venezuela to cut off relations with Colombia.”

“Venezuela has clear responsibilities,” he said. “Colombia has put forward serious charges. They deserve to be investigated.”

The conservative, American-allied Mr. Uribe has frequently feuded with the Socialist Mr. Chávez. Colombian officials have long complained that Mr. Chávez has harbored leaders of its main rebel groups.

Mr. Chávez has argued that American officials are using Colombia to portray him as a supporter of terrorist groups to justify a United States military intervention in Venezuela.