At least 13 Revolutionary Armed Forces of Colombia (FARC) rebels were killed in an air raid on a guerrilla outpost near Chigorodo by the Colombian air force, the head of the air force said Tuesday. General Hugo Acosta said on broadcaster RCN that it was possible Monday's attack killed as many as 20 FARC rebels. The air raid took place in north-western Colombia only 60 kilometres from the border with Panama.