The men were doing soldering work inside a pneumatic vibrator at a northern Colombian mine when they were fatally crushed by a load of coal.

“The Labor Ministry said the American company’s facilities where the deaths occurred lacked proper safety controls and equipment to ensure workers’ well-being,” AFP reported.

“The company now has several weeks to respond to the charges.”

According to Reuters, an unnamed ministry official said it was an administrative rather than a criminal investigation.

The official expected the case to be judged by two labour inspectors in a 3-4 month process and believed Drummond would most likely face a fine if there was a safety violation.

“A Drummond spokesman said the company had not yet been notified of the charges and so would not offer comment,” the newswire reported.