Islamic school UK
Illegal schools are often religious schools. Getty

Religious extremists are using illegal schools to teach children hate.

Some children are being taught that children can marry when they reach puberty, and other texts call homosexuality an "abomination"

Concerns have been raised about Christian, Jewish and Muslim schools, especially about 80 which are outside the control of Ofsted, the education regulator, The Times reported.

Robert Halfon, head of the Commons education committee, told The Times. "I have huge concerns about unregistered schools and the lack of regulation and inspection.

"Any school of any kind shouldn't be unregistered. There shouldn't be room for grey areas. Even if they have less than five pupils and are open less than 18 hours they should be inspected and registered."

Some children are being taught using texts from Abu Ameedah Bilal Philips, a Muslim preacher banned from Britain.

And Ivy Posen, 23, who attended an illegal ultra-orthodox Jewish school said: "They have a suspicious view of secular subjects... There was corporal punishment, no methods were off the table but it was usually a big wooden ladle."

About 25% of illegal schools are faith-based and they have been found in Luton, Birmingham and London boroughs.

In examples seen by the Times, children were taught it is okay to "give slight punishment to the wife" and celibacy is "disobedience to Allah."

Ofsted chief inspector Amanda Spielman has warned that religious hardliners were exploiting homeschooling rules.