The soldiers took part in an offensive in the rural area of Algeciras where troops and guerrillas have been fighting since Saturday.
In a statement, the army explained that one sergeant and two soldiers where found dead and two other soldiers injured in the battle.
It remains unclear what happened to three missing soldiers, the army said.
The source stated that military units in the area were able to confirm that a guerrilla leader known as “Calambrina” and members of his security ring were also killed in the clashes.
Defense Minister Rodrigo Rivera said that intelligence reports indicate that FARC guerrillas have intensified attacks against members of the security forces.
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