An Islamic faith school has lost its High Court bid to overturn a watchdog report condemning it as "inadequate" and placing it in "special measures".
A judge ruled there were "concerns" over School X entitling Ofsted to take action.
But Mr Justice Jay, sitting in London, rejected Ofsted's criticism of the school's policy for the segregation of boys from girls on the grounds of sex discrimination.
The judge said there was no evidence that segregation in School X "particularly disadvantages women".
Because of the public importance of the case, he gave both Ofsted and the school's interim executive board permission to appeal against his ruling to the Court of Appeal.