Labor camps are facilities where prisoners are forced to perform labor, usually under threat of torture or other physical harm.
The Cardassians kept labor camps on Bajor during the Occupation. In these labor camps operation was often aided by collaborators and some of the attractive women from the camps were taken to be comfort women for Cardassian soldiers. Bajoran religion within the camps was prohibited. Conditions in the camps were often brutal and hostile and the camps were often the targets for liberation by the Bajoran Resistance.
The Cardassians maintained the Hutet labor camp on Cardassia IV, which was overseen by a prefect. In this camp Bajorans, including Li Nalas, were still held for labor despite Cardassian claims all such prisoners had been released. After Li and other prisoners were freed by Kira Nerys and Miles O'Brien, the remaining prisoners were released and sent home to Bajor. (DS9: "The Homecoming")
The Romulans and the Breen also used labor camps. Fallit Kot was incarcerated for eight years in a Romulan camp for stealing a shipment of Romulan ale in 2362. (DS9: "Melora") In 2366, the Breen attacked a Cardassian ship, and used its crew to mine dilithium on Dozaria. (DS9: "Indiscretion")