BOGOTA, COLOMBIA - Colombia's government said on Thursday Venezuelan soldiers had blown up two small pedestrian bridges that stretch across their border in the latest incident to test diplomatic ties between the Andean neighbors.

Colombian Defense Minister Gabriel Silva said uniformed men apparently from the Venezuelan army blew up the bridges that cross into Colombia's Norte de Santander state in what he described as a violation of international law.

'Uniformed men, apparently from the Venezuelan army, arrived in trucks on the Venezuelan side at two pedestrian bridges that link communities on both sides ... and then proceeded to dynamite them,' Silva said.

Tensions are high between U.S. ally Colombia and Venezuela over a Colombian plan to allow the United States more access to its military bases as part of anti-drug and counter-insurgency cooperation against leftist guerrillas.

The long-simmering Andean dispute has in the past been mostly limited to diplomatic barbs. But the current crisis is raising the risk of more violence along the volatile frontier where rebels, drug gangs and and smugglers all operate.

Venezuela's President Hugo Chavez, a fierce U.S. adversary, has sent more troops to the border and told his military commanders to 'prepare for war' because he says the U.S. base plan could be used to stage an invasion of his OPEC nation.

Colombia's President Alvaro Uribe says the base deal is just an extension of current cooperation with U.S. troops. He has urged the United Nations and the Organization of American States to investigate Chavez's 'war threats.'

The two leaders have in past managed to work out their differences. But the current crisis is already cutting into their $7 billion a year bilateral trade, making this dispute more difficult to resolve.

Colombia's four-decades-old guerrilla war often spills over the frontier, where killings and kidnapping are common. Chavez accuses Colombia of not protecting its frontier while Colombian officials charge him with backing Colombia's FARC rebels.