The military junta led by the younger Deby has launched peace talks with various rebel groups who had long challenged his father's regime, but FACT has not taken part, insisting the transitional authorities first free its members.
While hundreds have been pardoned, most of the group's senior leadership, including leader Mahamat Mahadi Ali, remain in custody.
One newly released detainee, former maths teacher and FACT member Ouckonga Guelmine Kemnda, said calls for unity would ring hollow without their release.
"The government says it is open to dialogue and yet the person with whom it must dialogue is condemned," the 46-year-old said.
"When we want to talk to someone, we have to stay open," he added.
The transitional authorities have not commented on the detainees' statements or the outlook for the ongoing peace negotiations. The junta is set to stay in office at least through elections slated for October 2024.
