Colombia's environment minister has barred coal producers from loading the mineral onto ships until they comply with new, stricter environmental rules, a decision that affects U.S.-based Drummond and other miners.

Luz Helena Sarmiento, who traveled Wednesday to the Caribbean city of Santa Marta to verify the companies' alleged non-compliance with the new rules that took effect on Jan. 1, said the ban would be put in place immediately.

"There'll be no more coal loading (of ships) using barges at any port in the country. This not only applies to the company Drummond, but to any company that tries to export coal," Sarmiento said.

The minister acknowledged the decision would be "very costly for the country" because of lost royalty revenues, but she said coal loading with barges and cranes was putting the environment at risk.

The companies' failure to put in place a conveyor-belt system to directly load the coal also posed a threat to "Colombian authorities' institutional credibility."

The producers affected by the sanction will have five days to load the coal currently at port, according to Sarmiento, who said "it's preferable they finish loading the coal ... as opposed to leaving it there."

Drummond, which was fined $3.5 million last year for a January 2013 incident in which 500 tons of coals spilled into the Caribbean from a sinking barge, came under fire once again this week when port and environmental authorities complained that it was not complying with the new ship-loading rules. EFE