Newly unveiled plans to encourage more private schools to manage state funded schools will further erode the power of local education authorities to control admission policies, education experts warned this week.
Schools minister Andrew Adonis last week launched a prospectus encouraging successful private schools to get involved in running, setting up or sponsoring city academies.
He confirmed they would not have to provide the usual£2m sponsorship contribution.
The prospectus sets out how private schools can get involved in the management of state funded schools by "setting up, sponsoring and managing their own academies" or sponsoring a trust school maintained by the local authority to help it expand.
But the Institute for Public Policy Research (IPPR) is calling for urgent reform of the programme to build 400 city academies - many of which will replace secondary schools - so that admissions can be controlled by the local authority.
"Allowing more schools to control their own admissions will lead to a less effective and more unfair school system," said co-director Lisa Harker.
"The IPPR is concerned that this will ultimately lead to the end of schools with local authority controlled admissions," she added.
The criticism was rejected by the Department for Children, Schools & Families.
"We've introduced the new statutory school admissions code precisely to outlaw unfair and covert admission practices which can still penalise low-income families and increase social segregation," said a spokesperson.
Caroline Abrahams, programme director for children at the Local Government Association, said "over arching trusts" that would control admissions at trust schools in an area could help 'square the circle' between school autonomy and local authority control of admissions.