More than half of private Muslim schools have not been inspected for five years, while some have not received a full inspection for a decade.
News of the apparent gaps in monitoring comes as questions are being raised about whether some Muslim schools are adequately preparing children for life in Britain. The Government recently closed an Islamic school in East Sussex, which was raided by police as part of an anti-terror operation, because it did not meet registration standards.
Last month, King Fahad Academy, a west London school funded by the Saudi government, was condemned for using text books that described Jews as "pigs".
Muslim parents are increasingly choosing the private sector because they feel the state sector does not cater for their children.
Last month, the Muslim Council of Britain accused state schools of failing to respect Muslim wishes and called on headmasters to open prayer rooms, introduce single changing cubicles, overhaul sex education and reschedule exams outside Ramadan.
Why?These are not British values. The british flag is based on a christian symbol of the majority religion.
A report by the Open Society Institute says there has been a threefold increase in the number of private Muslim schools in Britain in the past 10 years.
Islamic schools on the DfES register are funded -privately, through the support of local mosques (supported by Saudi Arabia which promotes wahabi'ism, a form of Islam practiced by Bin Laden and his followers), other private funding and fees - of up to several thousand pounds a year - paid by parents. A number are registered as charities.
Like all the 2,000 independent schools in England registered with the DfES, they are not required to follow the national curriculum. They often devote a lot of time to Islamic studies.
A number of Ofsted reports are critical of poor buildings, inadequate resources, poor management, unqualified teachers and the low level of general education in some Muslim schools.
Mohamad Mukadam, the chairman of the Association of Muslim Schools, said: "Ofsted has the power to inspect independent schools and has not found anything that should worry people about Muslim schools.
"To judge our schools we need to look at the young people that are coming out of them and compare them with those -coming out of the comprehensive system. There is a marked improvement in the academic results being achieved in Muslim schools, a higher amount of young people progressing to higher education, and a far higher proportion going on to work in the professions."
Yes,and they are the same young people turning themselves into human bombs on the tubes and buses of London. The same young people demanding "Behead those who insult Islam".
With its ramshackle exterior, the School of the Islamic Republic of Iran in north-west London is barely recognisable as a school from the outside.
Behind wire gates, the main building is a grey-brick bungalow with a rusty iron roof and wire mesh over the windows.
The head teacher, Farzad Farzan, was reluctant to discuss teaching methods or syllabus, citing his "poor knowledge" of English and the absence of an interpreter.
He said: "We are an independent school and, therefore, we can choose what we wish to teach." Pupils followed a "Farsi syllabus". English was taught only once a week.
And why not? It's not as if the English have to speak English to live there.You can be Iranian, and so can your kids, their kids.