Police in Nigeria said they rescued 15 people chained up in a church in Lagos during the latest raid in a nationwide crackdown on religious institutions accused of abuse.
Detectives "stormed a prayer house used as a detention camp" on Wednesday evening and discovered 15 men and women aged between 19 and 50 chained by the legs, Lagos police spokesman Bala Elkana said.
The pastor of the church, "prophet" Sunday Joseph Ojo, and 10 others were arrested, Elkana said late Thursday.
The victims "were brought by their families to seek spiritual help from mental illness and other diseases," he added.
"The prophet said he has been in the healing ministry since 1986, (and) that he chained them in order to prevent escape."
Some of the victims had spent five years in the church, he said, adding that further investigations were taking place.
Non-government organisations first alerted police to Ojo's "Blessing of Goodness Healing Church" in the Ijegun area of Nigeria's most populous city, according to local reports.
The raid was the first on a church during a wider police crackdown on religious institutions -- the majority of which have been Islamic schools -- where inmates have been tortured, chained and sexually abused.
Hundreds of victims, mostly children, have been rescued in a series of raids over the past month, mainly across northern Nigeria.
Last week police rescued 108 "unfed and sick" inmates from a so-called reform centre in Kwara State, central Nigeria.
Religious institutions offering to "reform" victims of mental illness and drug abuse are common in Africa's most populous country in the absence of state support.