The entry policy of Jewish schools has been challenged by a campaign which opposes selecting children for state schools on the basis of faith.
The Fair Admissions Campaign has lodged complaints against 50 schools of different faiths with the Office of Schools Adjudicator, the body which regulates admissions to state schools.
FAC was co-founded last year by the Accord Coalition, an educational lobby group chaired by leading Reform rabbi, Dr Jonathan Romain.
A spokesman for the campaign said that it had chosen a cross-section of faith schools to see whether any of them were in breach of national entry regulations but it would not comment further until the OSA had reached a decision.
But it is understood that three Jewish secondary schools are among those who are the subject of complaints, including the country's largest, JFS. It received an unannounced visit from Ofsted last month, which is highly unusual for a school officially rated outstanding. It is not known if there is any link between the inspection and the complaint made to the OSA. Ofsted would not give details.
The OSA confirmed that it had received a "significant" number of objections from the FAC and it was in the process of sifting through them.
Rabbi Romain, who sees religious schools as socially divisive, said: "It is an investigative process, not targeting any one faith in particular, but looking at faith schools throughout the UK of all religious types. It is currently at a very early stage, with the idea being to see if there is any discernible pattern over religious admissions."
FAC believes faith schools should be open to all and that children should not be selected according to faith.