Newly appointed minister Pedro Sanchez said in an interview that the threat from the ELN guerrilla group "will be met with the legitimate full force of the state, to defend Colombians."

ELN guerrillas currently control a swathe of land near the Venezuelan border, where fighting has displaced about 56,000 people.

In a recent interview with AFP, ELN commanders vowed to repel a government counteroffensive and said years of "total peace" risk turning into "total war."

Sanchez dismissed the ELN as a "narco-criminal group" and vowed they would be met with "full force."

He also pledged to retake a major coca-growing region in the south of the country, a virtual microstate run by the Estado Mayor Central (Central General Staff).

Sanchez admitted retaking territory was a "wicked problem," but said it would be achieved.

"We're going to have to make a lot of sacrifice, we're even going to have tears, but in the end, we're going to achieve it."