In a statement, the rebel group ELN says it respects citizens' "right to vote freely" and adds that it does not want to "threaten any of the candidates or prevent people from voting."
Critics say that rebel groups in Colombia have taken advantage of ceasefires over the past four years to regroup, rearm and strengthen their grip on rural communities.
Meanwhile, the Colombian Ministry of Defense accuses the group, which has more than 6,000 fighters in Colombia and Venezuela, of profiting from illegal gold mining and drug trafficking.
Colombia's presidential election will be held on Sunday, June 21.
