BOGOTA (AFP) - Colombia on Thursday (May 5) authorised the use of all military force, including air strikes, against the country's three biggest criminal gangs in a major escalation against "organised armed groups".

Defence Minister Luis Carlos Villegas announced the directive late Thursday after a special session of a Senate committee in a violence-torn region of northwestern Colombia.

"Directive 15 permits the application of all the force of the state, without exception, against organised armed groups or groups who have major hostile capacity," he said.

Until now the military has been used only against leftist guerrilla groups, who have been negotiating an end to their half century old conflict.

The new strategy specifically targets three major crime groups - the Clan Usuga, Los Pelusos and Los Puntilleros.

"Those three organisations from today will be pursued autonomously or in coordination by the armed forces and the police," Villegas said, speaking from the region of Apartado, a stronghold of the Clan Usuga.

They have been classified as "organised armed groups" because they use camps, long arms, uniforms and have a territorial presence, he said.

A government source said that besides air strikes, the state's use of force could include "air assault operations with special forces, ambushes, high precision snipers, supporting artillery fire."