A Colombian official says that two units of the country's largest guerrilla army are balking at plans for them to disarm — raising possible problems for a peace treaty the government is negotiating with rebel leaders.

Inspector General Alejandro Ordonez says the 1st and 7th Fronts of the Revolutionary Armed Forces of Colombia are refusing to demobilize. His agency said Friday the two have about 800 members and are deeply involved in illegal mining and drug trafficking.

Ordonez's office is independent of the president and he has been a critic of the peace talks that are nearing a finish in Cuba.

President Juan Manuel Santos recently warned that rebels who reject a peace deal will wind up "in a grave or in a prison."