Striking workers at Drummond's Colombian coal mine will not go back to work after wage negotiations failed on Tuesday.
The country's coal output has been down by nearly one-third since labour action began two weeks ago, Reuters reports.
Drummond - Colombia's second largest coal producer - offered the main union, Sintramienergetica, a 5% pay raise for miners at its two operations; the union was asking for 9% and the company had previously offered 4.75%.
Sintramienergetica represents about 50% of Drummond mine and port workers - approximately 5,000 people - and has refused to participate in joint negotiations with the other two unions.
Aside from wages, another major sticking point is the 400 port workers that stand to lose their jobs when a conveyor belt renders them redundant next year. The union is asking that the company find alternate work for these employees; Drummond has said it will do so for 70%.
When labour action began in July, the coal miner declared 'force majeure' on some cargoes as it was unable to ship due to a lack of workers.
It's possible that a long-term Colombian strike could upset European coal markets by reducing surplus. However, under Colombian labour law strikes can last a maximum of two months before they are automatically lifted by an arbitration tribunal.
Last August, Drummond operations were cut drastically when a railway strike prevented stock from leaving mining sites.
Production from Colombia's largest coal producer, Cerrej??n, was also interrupted this year when workers went on a month-long strike. Negotiations ended with a 5.1% salary increase.