Health authorities in the Andean country have reported 702 cases and 10 deaths of COVID-19, which has been described as a pandemic by the World Health Organization.
"The National Liberation Army considers it prudent to declare an active unilateral cease-fire for one month, until April 30, in a humanitarian gesture from the ELN to the Colombian people, who are suffering from the devastation of the coronavirus," the leftist rebel group said in a statement published on its website.
The rebels, considered a terrorist organization by the United States and European Union, said its combatants will still defend themselves if they are attacked by Colombia's armed forces.
ELN units operate largely independently and some have ignored cease-fire orders from central commanders in the past.
The ELN called on the government of President Ivan Duque to meet its delegation from collapsed peace talks in Cuba to arrange a bilateral and temporary cease-fire.
Duque canceled possible negotiations with the group following a January 2019 car bomb attack at a police academy in Bogota that killed 22 cadets.
As a precondition to holding peace talks Duque has demanded the group, which has around 2,000 combatants, declare a unilateral cease-fire, including a suspension of kidnappings and attacks against the oil and gas industry, and that its fighters group together under international observation.
The ELN has rejected the demands.
In the statement, the rebel group also asked the government to reduce prison populations in the midst of the health emergency by freeing "political prisoners" and that it grant a subsidiaries to the unemployed and suspend loan repayments.The government was not immediately able to comment on the unilateral cease-fire or the ELN's demands.