Religious schools which separate boys and girls into different classes may split in-two in order to avoid punishment from Ofsted, it has emerged.

Headteachers have requested urgent clarification from the Government on whether their current practices will fall foul of the regulator after an Islamic school was judged to be breaching equality laws earlier this month.

The Sunday Telegraph has obtained a letter sent by one headmaster to parents at a north London Jewish school, informing them they may be forced to split into single sex schools amid a crackdown on gender discrimination.

It follows the Court of Appeal judgment last week, which ruled that co-educational schools cannot segregate pupils based on gender.

The ruling means that Al-Hijrah School, an Islamic centre in Birmingham, must end its policy of “complete segregation”, which previously stopped boys and girls from interacting at any stage of the school day.

The decision was welcomed by Amanda Spielman, Ofsted’s chief inspector, who said that the practice had placed “boys and girls at a disadvantage for life beyond the classroom and the workplace”.

However, the judgment is believed to have far wider implications for religious schools across the country, with Ofsted confirming there are at least 20 schools which it believes fall foul of equality laws.