The ministry said one of the underground mines inspected had no ventilation system in place and no equipment for measuring methane or other gas levels.

A total of 21 miners were killed in an explosion January 26 at a coal mine in northeastern Colombia due to an apparent buildup of methane gas. Six days later, on February 1, five coal miners were killed, also apparently due to a methane gas explosion, at an underground mine near the town of Sutatausa, north of Bogota. The inspections took place in the states of Norte de Santander, Boyaca and Cundinamarca, where a large number of the country’s underground coal mines are located.