Sintramineregetica union spokesperson Edgar Munoz confirmed to the Wall Street Journal that operations restarted Saturday night for the first time since late July at the Pribbenow and El Descanso mines.

“There is a partial restart of the operations now, and by Tuesday all workers should have reported back to their posts,” he said.

Another union official, Dorismel Caldera, said the decision may be appealed.

“They [the Colombia Labor Ministry] have gone over our heads and violated the right to strike,” the officials said.

Alabama-based Drummond ordered its workers back in an official announcement Saturday evening, following the Ministry’s order for an arbitration tribunal to resolve the dispute between it and the unions that has focused on salary increases for miners and port workers.

Drummond is the Andean 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 strike.

According to government data, output dropped 13% year-on-year during the first half of 2013 to 40.5 million metric tons. Part of this was also due to another work strike in March at Cerrejon that lasted a month.

Cerrejon is equally owned by Glencore Xstrata, Anglo American and BHP Billiton.

Colombia is the top coal producer in South America, and the fourth largest coal exporter worldwide.