Colombia has closed two thirds of the 30 mines where Colombian mining inspectors have run safety checks in recent days.
The death of 26 miners in two separate accidents earlier this year led the government to crackdown on dangerous mining practices.
The mining investigators have closed 20 mines, investigated over four days, which posed serious risks to human life, according to the Mines and Energy Ministry of Colombia.
One of the inspected underground mines also lacked ventilation systems and equipment for measuring methane and other gas levels.
The government has carried out the inspections in the states of Norte de Santander, Boyaca and Cundinamarca, where a large number of underground coal mines are located.