BOGOTA: A bomb on a bus detonated by suspected leftist militants in southern Colombia Tuesday killed three army troops and a civilian and injured another 16 people, local authorities said.

Authorities blamed the Revolutionary Armed Forces of Colombia (Farc) for the blast in Huila province, which occurred at about 2145 GMT.

The public bus was rigged with explosives and blown up outside a police station in Vegalarga, authorities said.

Founded in 1964, the Marxist Farc is Latin America's oldest and largest insurgency, with some 7,000 fighters, according to the Ministry of Defence.