Hundreds of men and boys have been rescued from a “house of torture” where they were allegedly starved and sexually abused, police say.

Nigerian Police have freed more than 300 men and boys, including children as young as five, who were being held in chains in a building in the Rigasa area of the northern city of Kaduna.

It is not known how long they have been there, but it is thought some may have been sent in the belief the building was an Islamic school.

A sign on the front of the building reads: “Imam Ahmad Bun Hambal centre for Islamic studies.”

However Kaduna state’s police chief Ali Janga told the BBC it was a “house of torture” and said it was being treated as a human slavery case.

Hundreds freed from 'house of torture' in Nigeria Show all 5 1 /5 Hundreds freed from 'house of torture' in Nigeria Hundreds freed from 'house of torture' in Nigeria Nigerian police have rescued more than 300 men and boys, some as young as five, from a "house of torture" in the Rigasa area of the northern city of Kaduna, 27 September, 2019. The detainees were allegedly sexually abused, starved and tortured while they were held captive in shackles. A sign above the building reads: "Imam Ahmad Bun Hambal centre for Islamic studies." REUTERS/Stringer Hundreds freed from 'house of torture' in Nigeria A boy who has injuries on his back is led away by police. REUTERS/Stringer Hundreds freed from 'house of torture' in Nigeria Some people are pictured with visible scars after being rescued from the building. Television Continental/via REUTERS Hundreds freed from 'house of torture' in Nigeria People are pictured with chained ankles and wrists. Television Continental/via REUTERS Hundreds freed from 'house of torture' in Nigeria A person with chained ankles is pictured after being rescued from a building in the northern city of Kaduna, Nigeria September 26, 2019, in this grab obtained from a video. TELEVISION CONTINENTAL/Reuters TV via REUTERS ATTENTION EDITORS - THIS IMAGE HAS BEEN SUPPLIED BY A THIRD PARTY.NIGERIA OUT. REUTERS TV Television Continental/via REUTERS

Images shared by police show shackles around the ankles and wrists of the detainees, some of whom had visible injuries.

Seven teachers at the school have been arrested.

Spokesman Yakubu Sabo said: “The state government is currently providing food to the children who are between the ages of five and above.

“We have identified two of the children to have come from Burkina Faso, while most of them were brought by their parents from across mostly northern Nigerian states.”

The children have been moved to a temporary camp at a stadium in Kaduna and will later be moved to another camp in a suburb of the city while attempts are made to find their parents, police said.

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Some parents who have already been contacted went to the school to retrieve their children.

One said: “We do not know that they will be put to this kind of harsh condition.”

Islamic schools are common across the mostly Muslim north of Nigeria – a country which is roughly evenly split between followers of Christianity and Islam.