BOGOTA, Colombia (AP) _ Colombian troops killed a regional rebel commander, the fifth guerrilla leader slain in less than a month, a top army general said Tuesday.

Luis Alexis Castellanos Garzon of the Revolutionary Armed Forces of Colombia, or FARC, died in a firefight Sunday night along with another rebel in Ubala, 30 miles east of Bogota, said Gen. Reynaldo Castellanos, commander of the army's Fifth Division.

The army believes Castellanos Garzon led a 1999 ambush on an army column that left 36 soldiers dead.

``We consider his death to be a major blow to the FARC,'' Castellanos told The Associated Press.

Castellanos Garzon's death follows that of four other guerrilla commanders in the Cundinamarca region, which borders the Colombian capital, Bogota.

Gen. Reynaldo Castellanos said better intelligence and more cooperation from local villagers had helped the military efforts to track down guerrilla leaders.

Separately, Colombian anti-guerrilla forces shot dead the No. 2 leader of the FARC's Arturo Medina unit, Luis Alberto Camacho Duarte, early Tuesday in the southwestern Narino province, the army said.

The conflict, which pits two rebel groups against government forces and outlawed right-wing paramilitary factions, kills an average 3,500 people, mainly civilians, every year.