Police in Kwara state have raided yet another private rehabilitation centre where they rescued 108 detainees with men, women and children found in shackles.
This is the sixth such raid by the police in a month following allegations of torture and abuse of detainees.
President Muhammadu Buhari had ordered that security officials crack down on these centres.
In the latest action, the police found the inmates in degrading conditions. The operator of the centre has been arrested.
Poorly regulated correctional facilities are common in Nigeria partly due to weak state educational and rehabilitation systems.
Parents usually send their children, who may be addicted to drugs or involved in petty crime, to change their behaviour but they end up being maltreated.
Kwara police commissioner Egbetokun Kayode told the BBC that the rescued victims are to be re-united with their families.
Rabiu Umar, who was at another rehabilitation centre that was raided earlier this month, told the BBC that he had been treated like an animal: