The report warns of covert selection

The London School of Economics study found one in four secondary schools in London used some form of selection.

And church and foundation schools were between three and four times more likely to adopt such selection criteria as other secondary schools.

The Department for Education says it is taking steps to ensure admissions are fairer, such as banning interviews.

Church and foundation schools have the freedoms proposed for the government's controversial new trust schools.

Allowing more schools to become responsible for their own admissions risks increasing the levels of covert selection LSE report

Trust schools, a new type of self-governing school authority which can oversee one or more schools, are proving a stumbling block for the government's new Education Bill - expected to be published by the end of February.

Over 90 "rebel" Labour MPs fear the proposed schools, which may be run by successful schools or outside providers such as universities, businesses and faith or community groups, will lead to a two-tier education system.

The LSE study found that 46% of voluntary-aided or church schools, and 35% of foundation schools, had admissions criteria which could allow some element of covert selection.

The figure for community schools (local authority controlled schools) was just 10%.

The report also found a slight increase in the proportion of schools selecting some of their pupils on the basis of aptitude for a subject - up from 5% in 2001 to 7% in 2005.

'Self-interest'

The report's authors, Hazell Pennell and Anne West, said those secondary schools responsible for their own admissions policy gave less priority to disadvantaged children, such as those in care, than other secondaries.

"More regulation is needed so that publicly-funded schools serve all children in a community and do not act in their own self-interest by 'selecting in' and 'selecting out' certain groups of pupils.

"The findings of our research suggest that allowing more schools to become responsible for their own admissions risks increasing the levels of covert selection," they said.

When examining "potentially selective" criteria, the report authors included: holding interviews with parents, selecting pupils by aptitude, using the recommendation of a primary school, the community involvement of parents and participation by pupils in organisations associated with the school.

A spokesperson for the Department for Education and Skills said selection by aptitude should not be seen as an unfair admissions criteria, as this was allowed under the law.

He said the report suggested that a minority of schools had the potential for covert selection, but that did not necessarily mean that it was occurring.

"We are banning interviewing in schools and tightening the admissions code so that schools must 'act in accordance' with it, rather than having to 'have regard' to it," he said.

"We have been clear since its introduction in 1998 that we intend the code to have real force."

Interviewing pupils is against the code of practice on admissions.