The rising number of schools in England with academy status could fuel rather than improve social segregation, says a report by the Academies Commission.
There were 2,456 academies open in England at the end of last year with Education Secretary Michael Gove continuing to push for the "mass academisation" of state schools.
However, the report 'Unleashing Greatness' suggests some academies may "covertly" select pupils by using extra information on families or holding social events with prospective parents.
The commission has recommended that academies should publish socio-economic data about who applies and who is offered a place in order to ensure children from minority backgrounds aren't excluded from the central government-funded system.
Shadow education secretary Stephen Twigg said: "This report highlights serious problems with Michael Gove's management of one of Labour's key school improvement programmes.
"The report issues a clear warning on the implementation of the academies policy, echoing Labour's concerns that under this government the schools system is becoming chaotic, impacting on standards and fairness."
In its report the Academies Commission says it has received evidence that some popular schools, including academies, attempt to select and exclude pupils.
It adds that, while this practice is not new, the fact that academies have greater autonomy over their admissions has "attracted controversy and fuelled concerns that the growth of academies may entrench rather than mitigate social inequalities".
The report is the biggest overview of one of the key structural change to theeducation system in recent years.
A spokesman for the Department for Education said: "All admissions authorities - be they local councils or self-governing schools including academies - must comply with our new fair admissions code.
"We specifically changed the law so that anyone who has concerns about how any state-funded school is admitting pupils can formally object to the OSA."
Posted 10/01/2013 by firstname.lastname@example.org