Sintramienergetica labour union’s Felix Herrera told Reuters that unsafe driving surfaces were related to the death last weekend of worker Dagoberto Clavijo, who died when the truck he was operating fell into Drummond's Pribbenow surface mine in Cesar province, northern Colombia.

Mine operations have been paralysed since more than 8000 direct employees and contractors stopped work on Monday to speak out against the conditions, Herrera said.

Drummond said Tuesday that the fatal accident last Sunday was being evaluated by “the competent authorities and the company", and called the strike illegal.

"The labour union organisation Sintramienergetica made the decision of carrying out an illegal stoppage of activities, affecting the normal operation of the company as well as the local, regional and national economy," the company said.

Drummond announced earlier this month that its Colombian output would jump 23% this year as it prepares to pull back the curtain on the new El Descanso Norte complex, which is set to commence production in the next few weeks.

Reuters reported that Drummond would pump $US1.8 billion in capital into the 5 million tonne per annum El Descanso Norte mine over the next two to three years.