Director of New Schools Network, Luke Tryl, said:
"While the increase in bursaries for lower income families is welcome, it is a drop in the ocean. Still only a very small minority of children from disadvantaged backgrounds receive support from the independent sector. It is not surprising that many state school leaders think independent schools need to do more to justify their social contribution claims.
"We know free schools are doing a fantastic job in increasing educational opportunity particularly for the most disadvantaged. We also know where independent schools are working in partnership with free schools - like at London Academy of Excellence and Holyport College - they are achieving remarkable success, opening doors and allowing children to reach their full potential.
"If independent schools are to remain charities with the tax benefits that brings, it is entirely right that they be expected to share practice, expertise and resources with state schools. Those independent schools that truly believe in making a social contribution should be committing their support to free school applicant groups across the country and play their part in ensuring a every child has access to an excellent school."