"It is simply an act of terrorism against two civilian trucks traveling on the roads of Arauca, which were set on fire and the drivers killed by members of the ELN," Colonel Miguel Angel Rodriguez - commander of a task force that operates on the border with Venezuela - told AFP, speaking about the region where the incident took place.
The ELN fighters ambushed the empty trucks yesterday, Rodriguez said.
Earlier yesterday, the government said it was postponing peace talks with the ELN rebels until they release an ex-lawmaker held hostage, just hours from the scheduled start of negotiations.
The rebels later began the process of releasing the hostage, Odin Sanchez, the government's chief negotiator in the talks said, adding that the process could take until next week.
More From This Section
The National Liberation Army (ELN) is Colombia's second largest rebel group, after the Revolutionary Armed Forces of Colombia (FARC), which has been in talks with the government for nearly four years.
Santos, the winner of this year's Nobel Peace Prize, has already signed a peace deal with the FARC, but voters rejected it in a referendum this month -- sending negotiators back to the drawing board.
Santos yesterday said the government still wants talks with the ELN to succeed.
However, the rebel group took issue with the postponement, tweeting, "We do not agree with the suspension of the timetable.