UK schools inspectorate Ofsted conducted a series of emergency inspections at the east London schools and found that six focused too heavily on Islamic teachings putting pupils' physical and educational welfare at serious risk.
"We asked Ofsted to carry out these independent school inspections and the findings are very concerning. All schools must prepare children for life in modern Britain," she said in a statement.
Mazahirul Uloom, a small secondary boys' school that professes to teach the "National Curriculum and Islamic Sciences", faces the most criticism. Some students there told inspectors: "Women stay at home and clean and look after the children. They cook and pray and wait for us to come back from school with homework."
The report also said there were no systems in place to check suitability of external speakers and staff recruitment checks were not rigorous enough. In his letter to Morgan, Ofsted chief Sit Michael Wilshaw said: "I believe that, in all six schools, pupils' physical and educational welfare is at serious risk... Pupils in these schools may be vulnerable to extremist influences and radicalisation."
The other schools named on the risk list include Jamaitul Ummah, Ebrahim Academy, London East Academy, Al Mizan and East London Islamic School.
The report comes a day after details leaked of a report on another school, Sir John Cass Foundation and Redcoat. It was the only non-Muslim faith school to be inspected as part of the same set of snap inspections to have been pulled up for not safeguarding and monitoring pupils adequately.
Under the UK government system, schools are allowed to run on a faith-based principle within a broader national curriculum. They are required to admit a percentage of pupils from all other faiths and also teach about all faiths equally.
All independent schools, academies and free schools also have to adhere to the Independent School Standards (ISS), which demand that schools encourage pupils to "respect" British values.
The six private schools pulled up are all in Tower Hamlets, an area of east London predominantly populated by Bangladeshi-origin Muslims.