The National Liberation Army (ELN) made the announcement Tuesday via a body called its Central Command. The ceasefire is due to begin August 3.

Defense Minister Ivan Velasquez told reporters the government would issue a decree ordering a halt to army offensive action starting Thursday.

Founded in 1964, the ELN had more than 5,800 combatants in 2022, according to authorities. It is Colombia's last active guerrilla group.

On June 9, Colombian negotiators signed a six-month ceasefire agreement with the ELN.

If it holds, the ceasefire would be the longest ever agreed to by the ELN, which has taken part in failed negotiations with Colombia's last five governments.

Peace talks are due to resume August 14 in Venezuela.

Last week government forces killed six ELN soldiers in eastern Colombia.

President Gustavo Petro, a former guerrilla, came to power last August pledging a policy of "total peace."

The much larger Revolutionary Armed Forces of Colombia, or FARC, laid down arms in a historic peace accord reached in 2016.