Colombia's mining minister has gone to the scene of the country's latest mining disaster and says the nation has just 16 safety inspectors for 3,000 mines.
Officials suspect a methane gas buildup caused the blast at the La Preciosa coal mine that killed 21 workers Wednesday. Methane gas is also believed responsible for a 2007 disaster at the same mine that claimed 32 lives.
Mining Minister Carlos Rodado said in a radio interview Thursday that the latest disaster should prompt more investment in mine safety.
La Preciosa passed a government safety inspection in November.
The mine has been closed pending an investigation, which will determine whether it will reopen.
Colombia is South America's top coal exporter.