More than half of all independent schools still do not allow state school pupils to share their facilities, despite the Government's efforts to encourage more partnership between the two sectors.
And almost one in 10 of the private schools which have collaborated with the state sector admitted charging more than the going rate for facilities to make a profit from state schools, a survey of 900 fee-paying schools found.
Almost 70 per cent of fee-paying schools reported that they had not opened their specialist teaching facilities such as classrooms, science laboratories, or drama studios to local state schools, according to the study by the Independent Schools Council (ISC).
The ISC released the study as part of the sector's campaign to be allowed to keep its charitable status.
Last year, a report by the Cabinet Office's strategy unit recommended that private schools should only be allowed to keep their charitable status and the tax benefits that come with it if they can demonstrate their "public benefits".
The Government has yet to publish its proposals but loss of charitable status would be a severe financial blow for even the wealthiest private schools.
Dick Davison, of the ISC, defended private schools against accusations that they were still ignoring attempts to foster closer links with the state sector. He argued that collaboration was limited by the fact that it was often logistically very difficult, if not impossible, for schools to share facilities.
"In many cases it is simply not possible to find times when it is possible to share these facilities," he said. "It is also worth saying that many maintained schools have no need - in some cases they actually have better facilities than independent schools."
Much of the co-operation between the two sectors involved teachers working together, something that did not show up in the ISC's survey, he added.
Schools which responded to the survey also blamed state schools for the poor take-up. "Occasionally prejudice, ideology or discourtesy play a part. Offers were ignored or refused," the report concluded."And occasionally an offer is blocked, maybe for good reasons, by the local education authority."
The report said nearly 90 per cent of 10 schools had made at least one facility available to community groups, private firms or state schools. But it said they were more likely to share their facilities with companies than state schools.Reuse content