SAN ANTONIO, Venezuela, (Reuters) – Venezuelan  soldiers blocked the main border crossing with Colombia yesterday after President Hugo Chavez’s government said  paramilitaries were behind the killing of two soldiers.

In the latest violence in an often lawless region between  the Andean neighbors, a gang of four men on motorbikes ambushed  and shot dead the Venezuelan soldiers at a checkpoint in  western Tachira state  on Monday.

Venezuela blamed Colombian paramilitaries for the murders,  ratcheting up the diplomatic feud between Chavez’s leftist  government and the administration of Colombian President Alvaro  Uribe, who is Washington’s main ally in the region.

“Sadly, our two men were brutally murdered by groups  operating in the frontier zone, trying to spread fear and  create an atmosphere of insecurity,” local army head Franklin  Marquez said. The pair were shot in the back in apparent  revenge for a crackdown by security forces, he added.

Paramilitary gangs, originally set up to fight Colombian  guerrillas, operate in the border area, as do rebels, and a  host of criminal gangs trafficking gasoline and drugs.

Witnesses in the Venezuelan border town of San Antonio said  dozens of soldiers with an armoured car and machine gun had  taken over the road to the nearest Colombian locality, Cucuta.

While large queues of cars formed on both sides, hundreds  of locals crossed by foot under a bridge, loaded with suitcases  and bags of goods, Reuters witnesses said.