The National Liberation Army (ELN) and the administration of President Juan Manuel Santos, which started formal talks in February, began a fresh cycle of negotiations this week. Both sides say they want to work toward a ceasefire.

"This would be a starting bilateral ceasefire, it's not the end of the conflict, it's temporary - with the possibility of extending it to generate trust," Bernardo Tellez, a member of the ELN negotiating team, told journalists in Quito.

"The idea is for the temporary ceasefire to be for three months and to take actions to alleviate the civilian population," he added.

Santos has in the past demanded that the rebels end all kidnappings and attacks on oil infrastructure. A recent bomb attack by the rebels has kept the Cano Limon crude pipeline stopped for 56 days.

The ELN has some 2,000 combatants and has long been considered a terrorist organization by the United States and the European Union.