The ministry said this week that it had inspected the 30 operations over four days, and that the 20 ordered closed had “posed serious risks to human life”. One of the noncompliant mines had no ventilation system in place and also had no equipment for methane monitoring.

"In almost all the mines [inspected] there were health and safety hazards," Mines and Energy Minister Carlos Rodado said.

The inspections were performed in the states of Norte de Santander, Boyaca and Cundinamarca. The last of the three has a high concentration of the country’s underground coal operations.

Rodado said the ministry had developed a plan to provide employment to the workers affected by the temporary shutdown.

"We're doing this shock plan not to close mines but to save lives, and to fulfill the rules of mining safety," he said.

"We want to protect the workers."

The inspections followed the deaths of 26 workers in two separate mine explosions since the beginning of this year.

The first of the two occurred January 26, when 21 miners were killed in an explosion in northeastern Colombia due to an apparent buildup of methane. Just six days later on February 1, five more workers died in another apparent gas-related explosion at an underground mine near Sutatausa, north of Bogota.

Rodado said that, following that pair of accidents, just 16 inspectors were working in the country, which has about 6000 legal and illegal mines. According to Dow Jones Newswires, President Juan Manuel Santos has called for the immediate hiring of more inspectors.

About 100 miners were killed in mining accidents in Colombia in 2010.

The mines of Colombia, the world’s fifth-largest coal exporter, are largely controlled by foreign companies, including Glencore International, BHP Billiton, Xstrata and US-based Drummond.