The Alabama-based company was hit with a government-ordered loading suspension at its Santa Maria port after one of Drummond’s loaded barges nearly sank.

The suspension from February 6 prevented the company shipping its exports, reportedly costing it $6.4 million per day.

Luz Helena Sarmiento, general director of the National Environmental Licenses Authority, or ANLA, said it reviewed Drummond's contingency plan and would now end the loading suspension.

"The reopening of loading activity with barges does not mean the end of this investigation, it is an ongoing punitive process that will determine whether it was an accident or negligence," Sarmiento told Reuters.

"It is possible it is a serious offence and, if applicable, the penalty shall be proportionate to the damage and exemplary," she added.

The Environment Ministry demanded a contingency plan from the coal giant, which released the findings from an internal investigation on February 14.

“Drummond regrets the occurrence of this industrial accident but that is exactly what it was, an industrial accident with no intent to harm the environment, but conversely actions were taken to minimise damage to the environment,” a company statement said.

“Despite the most careful attention to detail and planning to avoid this type of incident, industrial accidents do occur.”

Sarmiento said a ban would also be lifted on overnight transport on Colombia's main coal railway, known as Fenoco.

A regional environmental body ordered Fenoco to stop trains running near populated areas so residents would not be disturbed. The company has complied with the order since early February.

Colombia’s largest coal exporter, Cerrejon, has also been inactive since the beginning of the month due to employee strike action. Negotiations continue in what is now the third week of the strike.

Javier Garcia, head of corporate mining for the Ministry of Mining and Energy, told Bloomberg Friday that the shutdowns in the mining sector were costing Colombia 192,000 tons of exports per day, affecting 79% of the country's output.