The Columbian Government has shut down 18 illegal gold mines as part of an effort to regulate the industry and mitigate environmental hazards to workers.

The mines that received closure notices are located in the departments of Antioquia and Cordoba in northwestern Colombia.

About 48 mines have received closure orders since August 2010.

The Environment Ministry said officials are reviewing the legality of at least 571 mines across the country, reports Businessweek.