The group, usually known by its Spanish acronym, FARC, said Kevin Scott Sutay, who served in Afghanistan as an explosives specialist with the U.S. Navy, was taken prisoner June 20, Latin Times reported.
"Despite the right we have to hold Kevin Scott as a prisoner of war, we have taken the political decision to free him in the spirit of talks that are advancing in Havana with the Colombian government," a FARC statement said.
The group did not go into details about Sutay's capture. The statement suggested he was taken prisoner in San Jose Guaviare, a town in southern Colombia near a military base.
FARC said Sutay is from New York and traveled to Colombia overland through Mexico and Central America.
The government and FARC have been involved in peace talks in Havana since November and appear to have made significant progress in recent months, the report said.