Hugo Chavez, Venezuela's president, has threatened to cut off oil exports to the United States if US-allied Colombia launches a military attack against his country.
"If there was any armed aggression against Venezuela from Colombian territory or from anywhere else, promoted by the Yankee empire, we would suspend oil shipments to the United States even if we have to eat stones here," Chavez said on Sunday.
He added that he had cancelled a trip to Cuba because he had intelligence revealing that "the possibility of an armed aggression against Venezuelan territory from Colombia" was higher than it has been "in 100 years".
Chavez, a leftist and vocal critic of the United States, broke off diplomatic relations with Colombia last week over claims by the outgoing Colombian President Alvaro Uribe, a close US ally, that his country harbours Colombian rebels.
Uribe had said that top commanders of the rebel Revolutionary Armed Forces of Colombia, or Farc, have taken refuge in Venezuela and were launching attacks against Colombian troops.
The Colombian government had presented photos, videos and maps of what it said were Colombian rebel camps inside Venezuela to the Organisation of American States.
Chavez has dismissed the accusations as a bogus show intended to smear his government and has said that Uribe could be trying to lay the groundwork for an armed conflict with Venezuela.
The Colombian government denies seeking a conflict and says it went to OAS with its evidence about the rebels last week because Chavez's government had not taken steps to address the situation.
The United States threw its support behind its key ally Colombia, calling Chavez's decision to sever diplomatic relations and put border troops on alert "a petulant response" to Bogota's accusations.