Ministers are attempting to smooth fears from Liberal Democrats that free schools will entrench social division.
Twenty-four state-funded independent schools are due to open this term and more are expected to follow.
Michael Gove, the education secretary who has championed the policy, denied that he wanted free schools to make profits.
Deputy prime minister and Liberal Democrat leader Nick Clegg was said to have exerted pressure on the issue, but Mr Gove claimed the two were in agreement.
Free schools are able to vary pay and conditions of teachers, breakaway from the national curriculum, are funded by central government and exist out of local authority control.