Police said on Saturday they'd freed nearly 150 students from a purported school in northern Nigeria.
It claimed it was teaching the Koran but had instead subjected them to abuse.
One of the rescued captives, Ibrahim Musa (SOUNDBITE) (English) RESCUED CAPTIVE, IBRAHIM MUSA, SAYING: "They chain you up, with your legs and your hands and they beat you for a while and leave you in one corner for a while, so it is extreme punishment for talking about the conditions here." The raid was the fourth such operation in a month.
It brings the total released from religious schools in northern Nigeria to more than 1,000.
It will put more pressure on President Muhammadu Buhari to take action on loosely regulated Islamic schools.
Experts say such instititions teach millions of children across the mainly Muslim north of the country.