Mexico’s independent National Human Rights Commission said Wednesday that 90 people have died since 2006 in mine accidents in the northern state of Coahuila, the country’s main coal-producing region, attributing the fatalities to poor safety conditions.

Federal authorities have shut down 12 mines in northern Mexico after inspections spurred by an accident last month that claimed the lives of 14 workers, the labor department said. Inspectors have already visited 41 of the 100 sites on their list, the department said in a statement.