Only one of 17 Jewish institutions that were suspected of being unregistered schools is currently under investigation by Ofsted.
Most of the others remain beyond further scrutiny by the inspection service because of what it regards as a loophole in the law.
The figures were presented in a witness statement to the Independent Inquiry into Child Sexual Abuse by Sophie Young, Ofsted’s principal officer for independent and unregistered schools.
According to her disclosure, Ofsted has visited 314 institutions suspected of being illegal schools of which 31 were religious.