Colombia's president has fired his armed forces chief for verbally maligning prosecutors involved in investigations of officers accused of ordering extrajudicial executions.

President Juan Manuel Santos told reporters Tuesday that Gen. Leonardo Barrero was being relieved for insulting the judiciary and nation in a phone conversation published over the weekend.

The conversation was recorded by prosecutors investigating graft by senior officers in allegedly inflated military contracts and was revealed by the newsmagazine Semana.

In one recording, Barrero is heard telling a colonel jailed in an extrajudicial killings case that prosecutors are "a bunch of crap" and suggesting a counterattack be mounted to discredit them.

Colombian soldiers are accusing of committing hundreds of extrajudicial slayings through 2008, dressing victims in fatigues and presenting them as guerrillas killed in combat.