An Islamic independent school, previously criticised for not treating boys and girls equally and failing to promote "fundamental British values", has now been found to segregate male and female staff by using a dividing screen across the middle of a classroom.

Rabia Girls' and Boys' School in Luton was criticised following a previous Ofsted inspection, after it was previously graded as "inadequate" in its standard of teaching and achievement of pupils. The Ofsted inspection, in 2015, found girls and boys were not treated equally as they did not have the same educational experiences and opportunities. These include girls not having the same access to science laboratory facilities as boys and the design and technology curriculum at the school limiting girls to activities "related to knitting and sewing".

Following an emergency follow-up inspection of Rabia Girls' and Boys' School and two other independent schools, requested by the Department for Education (DfE), Her Majesty's Inspectors (HMI) chief inspector Sir Michael Wilshaw wrote a letter to education secretary and minister for women and equality, Nicky Morgan, voicing concerns about segregation in independent faith schools.

He wrote: "HMI who inspected the Rabia Girls' and Boys' School in Luton expressed their concern when, at the initial meeting with inspectors, the school insisted on segregating men and women through the use of a dividing screen across the middle of the room. This meeting was not carried out in a religious setting but in a classroom. HMI also gathered evidence that male and female staff are segregated during whole-school staff training sessions. Male staff sit in one room and the session is simultaneously broadcast to female staff in another part of the school."

HMI said they were "so concerned about the behaviours modelled by the leaders of this school" that it would remain in the inadequate category despite improvements being made elsewhere.

Wilshaw added: "Despite the changes introduced in 2014 by the DfE to strengthen the independent school standards in relation to fundamental British values, it is clear that these are not being followed by some independent schools. Indeed, it is my view that these revised standards are being actively undermined by some leaders, governors and proprietors.

"HMI will remain vigilant in ensuring that such behaviour, which clearly flouts the requirement to promote British values, is identified and reported. Any form of segregation, without a good educational reason, is likely to lead to an inadequate inspection judgement for leadership and management.

"I urge you, Secretary of State, to further review the DfE guidance to independent schools on these matters and, if necessary, write to the proprietors of independent faith schools to clarify your expectations and to reaffirm the government's commitment to the promotion of British values."

A DfE spokesperson said: "It is completely unacceptable for women to be treated less favourably than men, and the advice note we have received from Ofsted on Rabia Girls' and Boys' School is extremely concerning.

"We have referred this case to the EHRC so they can consider whether the school has breached the Equalities Act, and we will consider carefully the inspection report on the school to determine what action to take against any potential breaches in the independent school standards."

IBTimes UK has contacted Rabia Girls' and Boys' School for comment.