This time, the building was discovered in President Muhammadu Buhari's hometown, putting pressure on him to act against the practice of sending children to institutions run by Islamic scholars rather than conventional schools. The children are often sent out on the streets to beg.
More than 300 boys had been held in the building raided on Monday in Daura, Katsina state police spokesman Gambo Isa told The Associated Press. The building was discovered when some of the boys escaped on Sunday and protested against excessive torture.
"Many of those rescued have been sent to hospital on account of the ill treatment they suffered," Isa said. "Some of them are unable to walk because of the injuries they sustained after being chained for several years."
The building's owner and others involved were arrested, Isa said, and 67 boys were rescued. Search parties were looking for the ones who had escaped.
Some of the boys had been enrolled by their families for Quranic studies, Isa said. Others had been sent there because of delinquency or for treatment for drug addiction in an attempt at "character remodeling."
Police said the school's proprietor, 78-year old Bello Mai Almajirai, "has been in the business for more than 40 years and now he has become old he no longer has the capacity to run the rehab Islamic school."
The raid follows one late last month in Kaduna city, where police discovered some 400 boys and young men. Marks on their bodies showed that some had been tortured, police said.
The office of Nigeria's president did not immediately comment on the latest raid.
An aide to Buhari, who comes from the north, earlier this year noted the widespread view that the "almajiri" learning system associated with begging was a "security challenge and a scar on the face of Northern Nigeria."
But the aide, Garba Shehu, rejected reports that the president had banned the system. "The federal government wants a situation where every child of primary school age is in school rather than begging on the streets during school hours," he said. "At the same time, we don't want to create panic or a backlash."
Many Nigerians have expressed concern that some who study at almajiri institutions are prone to religious extremism.
Umar reported from Maiduguri, Nigeria.
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