A centre where the almajirai are reportedly tortured in dehumanising conditions has been discovered in Niger State.
Fifteen of the almajirai were rescued, some of them with scars, and some in shackles.
The centre located in Anguwan Gwari Suleja was conceived as an Islamic school. Some of the pupils are as young as five years.
Different iron tools reportedly used to carry out torture were discovered by the police who visited the facility following complaints by residents of the area.
The operator of the centre, Umar Ahmed, 46, was arrested.
Police spokesman Abiodun Wasiu said three chains were recovered from the torture centre, adding that the 15 persons rescued were handed over to the Niger State Child Rights Agency, while the operator of the centre would soon be arraigned in court.