A report commissioned by the British government found evidence of a coordinated effort to Islamise state-run schools in the city of Birmingham by taking control of their governing bodies.
The investigation into allegations of a hardline Muslim "plot" at state-run schools said that people in positions of influence had tried to introduce "intolerant and aggressive" Islamic beliefs.
The report by former police counter-terrorism chief Peter Clarke said it had neither looked for, nor found, evidence of violent extremism, terrorism or radicalisation in the schools in England's second city.
But the damning conclusions reported "clear evidence" that some of those working in schools and governing bodies "espouse, endorse or fail to challenge extremist views".
The report noted a discussion on instant messenger service WhatsApp between teachers and the acting principal at one school, which revealed explicit homophobia and anti-Western, anti-US and anti-Israeli sentiment.
Participants in the discussion last year suggested the Boston bombings and the murder by two Islamists of British soldier Lee Rigby in London were hoaxes.
Education Secretary Nicky Morgan told parliament the report was "disturbing" and announced measures to regulate more closely who was involved in running schools.
"There has been coordinated, deliberate and sustained action ... by a number of associated individuals, to introduce an intolerant and aggressive Islamic ethos into a few schools in Birmingham," Clarke's report said.
"This has been achieved by gaining influence on the governing bodies, installing sympathetic head teachers or senior members of staff, appointing like-minded people to key positions, and seeking to remove head teachers they do not feel to be sufficiently compliant."
The report added that the intent was to impose upon pupils "the segregationist attitudes and practices of a hardline and politicised strand of Sunni Islam".
The investigation was sparked by the so-called "Trojan Horse" letter, sent to local authorities in November detailing an alleged plot to take over schools.
The anonymous claim reignited debate about multiculturalism in Britain and renewed concerns about the risk to young people of Islamic extremism - a major issue as hundreds of Britons head to fight in Syria.
Some community leaders in Birmingham, which has one of Britain's largest Muslim communities, said the row was baseless and driven by Islamophobia.
But Prime Minister David Cameron called for schools to teach "British values", arguing that tolerance of many faiths and cultures has gone too far in allowing extremism to flourish.