The toxic fallout of a grisly army scandal continues to spread in Colombia, as more soldiers are arrested over their alleged roles.

In recent days another three colonels have been arrested, bringing the total number of military personnel captured to at least 22.

The "false positives" scandal has revealed that the army murdered civilians, who were then dressed in rebel uniforms or given guns. They were then presented as guerrillas or paramilitaries killed in combat.

These allowed units to fabricate results, and officers to gain promotion.

The number of victims is believed to be in the thousands.

"The issue of the false positives puts into doubt the doctrine of the security forces with respect to human rights," said Maria Victoria Llorente, director of the think-tank Foundation Idea for Peace. "This puts at risk a prized value for the military: legitimacy."