Ofsted chief Sir Michael Wilshaw is to say seven schools in Tower Hamlets must take more action to protect students

An outstanding state secondary school and a group of independent Muslim faith schools in London’s east end are to be criticised for safeguarding failures and branded as inadequate after Ofsted inspectors raised a string of concerns over protecting pupils from extremism, the Guardian has learned.

Among the issues highlighted were sixth formers at one school posting links to Islamist extremist matter via a Facebook page claiming to be associated with the school, and separate entrances for boys and girls at the same school.

Sir Michael Wilshaw, Ofsted’s chief inspector, is to publish the watchdog’s analysis of snap inspections of eight Tower Hamlets schools in an advice note to the education secretary, Nicky Morgan, on Friday, with the Department for Education due to publish its response on the same day.

Ofsted found that sixth formers at Sir John Cass secondary school in Stepney had posted links to Islamist extremist material via a Facebook page claiming to be associated with the school, and that the school’s leadership had failed to act appropriately after being informed.

The school was also found to have separate entrances and areas for boys and girls, which it said was a “historic” arrangement dating back to the 1990s.

Robert McCulloch-Graham, corporate director of education for Tower Hamlets council, said it accepted Ofsted’s report, which downgrades the school from outstanding to inadequate and places it in special measures, because failures of safeguarding and management.

“It’s unfortunate because Sir John Cass is an outstanding school in many other ways, for its results and the journey it has been on. But there was an incident and Ofsted were right to criticise it, and we’ll put in support for the school to turn it around as quickly as possible,” McCulloch-Graham said.

Of the Facebook page, he said: “I haven’t got all of the details but we understand it was put up by some sixth formers, we believe, external to the school, but it did advertise events at the school. The school was alerted to it some time ago and the criticism is that the school should have done more to prevent the site carrying on, and should have done some follow-up actions to try and mitigate some of the influences the site may have brought to bear on the students.

“It is a bit for shock for us but we can’t get away from the fact that there weren’t good actions taken following the discovery of the website and we should have placed more emphasis on what should have been done.”

A second state school, Marner primary in Bow, was praised by inspectors for promoting British values, as required under recent government guidelines.

Ofsted’s inspection reports and advice note come after Morgan assured the House of Commons education committee there were no signs of extremism on the scale seen in Birmingham schools investigated as part of the alleged Trojan horse infiltration plot by conservative Muslims.

“Ofsted have been into Tower Hamlets, particularly in relation to the Marner Primary School. They inspected them in September and they found that there were no matters requiring further measures,” Morgan told the committee last month.

Six independent Muslim schools in the borough were also inspected and given action plans by Ofsted detailing improvements required in safeguarding and other areas. The schools inspected include Ebrahim College in Whitechapel and two schools supported by the East London mosque, as well as the academically successful Jamiatul Ummah boys school in Shadwell.

A spokesman for Ofsted said the inspection reports would be published on Friday.

Sir John Cass school – full name Sir John Cass Foundation and Red Coat Church of England secondary school – was thought to be one of the worst performing state schools in the country before its current headteacher, Haydn Evans, took over in 1995. Its results have improved dramatically over the years.

On Wednesday the University of East London awarded an honorary doctorate to Evans for his services to education.