Nigerian police have rescued 259 captives from an illegal detention centre in a mosque in Ibadan, in the south-western state of Oyo.
The owner of the facility and eight others have been arrested, according to local media.
Conditions at the mosque were inhumane, Mr Shina Olukolu, state commissioner of police, told the Punch newspaper.
In the past month, more than 1,000 people have been rescued from similar institutions in Nigeria.
Local police raided the centre on Monday evening after a tip-off from a 17-year-old who had escaped from a similar centre in the area.
Some of the victims reportedly told police they had been held there for years.
This is the latest raid in Nigeria's crackdown on "rehabilitation schools" for drug addicts, troublesome children and people who have committed petty crimes.
Officials have likened the facilities to torture centres, and have vowed to close them down.
People rescued from similar institutions over the past month have reported physical and sexual abuse.
Lawal Ahmed was rescued from a rehabilitation centre earlier in October. He told the BBC that beatings and abuse were commonplace.
He said: "They make a cover story and say they are teaching us. They are not teaching us for the sake of God. Everything we are doing is by force and punishment.
"Whoever tells you they are performing prayers here for the sake of God, they are lying."