According to the army, a military patrol caught the guerrillas red-handed when collecting an extortion payment from a local farmer.

The rebels called a unilateral ceasefire to support ongoing peace talks in December, but have continued criminal activities related to drug trafficking and extortion, according to the authorities.

In a report on the FARC’s now three-month-old ceasefire, the country’s Ombudsman’s Office said on Saturday to be concerned about 33 “other types of action that turn out to be clear violations of human rights or breaches of international humanitarian law.”

According to the governmental human rights monitor, civilians in FARC-controlled areas continue to be victim of “threats, extortion, kidnapping, selective homicides, land mine accidents, mobility restrictions, the imposing of ‘manuals of conduct’ and forced displacement.”

The alleged continuation of criminal activity by the rebels has been the main reason for Colombia’s conservative opposition, under the leadership of former hard-line president Alvaro Uribe, to reject the FARC’s ceasefire.

The rebel group and the government have been negotiating an end to the 50-year-long armed conflict in Cuba since 2012.

Since then, partial agreements have been reached on rural reform, the FARC’s move from war to politics, and the rebels’ abandoning of drug trafficking, one of the guerrillas’ main sources of income to fund their war.

Two negotiating teams are currently negotiating in Colombia; the main delegations are negotiating victim compensation and a sub-committee is negotiating a bilateral truce that could come into force before an eventual final peace deal.

To support the de-escalation of the armed conflict while the talks are ongoing, President Juan Manuel Santos ordered a month-long suspension of air strikes against the FARC, while the guerrillas vowed to help the military in clearing minefields.

If successful, the peace talks will end a war that has been waging in Colombia since 1964 and has left more than 7 million victims.