The official told Reuters the 53-day strike at operations owned by US-based miner Drummond, paired with a month-long February walkout by Cerrejon workers, made for a tough year that cut into exports and royalty revenue. Stoppages at Drummond’s port facility as well as railroad disruptions were no help.

“We're going to struggle to meet this goal, that’s clear,” he said.

“But we're going to make every effort to somehow overcome the impact that this conflict has had on production.”

Both strikes centered on pay issues and working conditions, and the Drummond walk-out also involved planned layoffs of port workers in 2014.

Drummond, which recommenced operations September 14 and realised full production levels this week, was forced to declare force majeure on shipments during the strike.

However, Acosta noted government officials were yet to evaluate the impact of the Drummond strike on coal output for the year.

“It's a matter of waiting for the company to reschedule its activities and eventually recover some of its production that it didn't mine during the stoppage,” he said.

Colombia, the largest coal producer in South America and the fourth largest worldwide coal exporter, sends much of its tonnage to the European market. While it did lose about one-third of its output during the most recent strike, prices suffered little change because of sufficient supply.

Drummond is the nation’s second largest producer; it produced and exported about 26 million metric tons of coal last year.

Colombian media said the government lost an estimated 106 billion pesos ($US850,000) daily during the Drummond strike.