Pupil mix in the Capital's classrooms is being undermined by selection according to a report by a leading think tank.

The Institute for Public Policy Research claimed the current system of giving state schools their own admissions policy is undermined because London has a pattern of popular and unpopular schools.

Popular schools select their pupils and as a result choice means little to many parents.

The think tank argued London schools need a system that reflects the variety of aims of a public education service, in addition to parental preference.

Instead of the current arrangements, admissions should be decided by communities, as represented by their Local Education Authorities.

The IPPR, which has played a key role in formulating government education policies, argued the admissions procedures of controversial city technology colleges and academies should also be brought under the control of LEAs along with all the other schools in their areas.

Creating a more even balance of pupils in schools would drive up exam results in poor-performing schools, the think tank claimed.

"There is growing evidence that the pupil mix is a vital factor for school performance," said IPPR research fellow Martin Johnson.

"Pupils could be admitted to a federation rather than a school. They would be placed in, and possibly moved between, schools on the basis of a balance between parental preference, child's preference, child's need and community interests.

"It must be recognised that some London schools would require some persuasion or compulsion to accept this, but for the sake of London's children this nettle must be grasped," he said.