If independent schools refuse to sponsor an academy, they should be stripped of their status as a registered charity.

That is according to Alan Milburn, the government's social mobility tsar, who described the charitable status afforded to these schools as a disguised tax break.

This status is unjustified, Mr Milburn said, unless they are prepared to "give something back", by which he means sponsoring an academy.

He has, therefore, called for the government to overhaul the system in an effort to ensure that schools are not abusing their charitable status.

Speaking to The Times, Mr Milburn explained: "Frankly the tax break shouldn't be given just because on occasions the private school opens its playing field to the state school. It's got to go beyond that.

"I think the Charity Commission got it wrong in the way they interpreted the public benefit test. I would make a condition of charitable status for private schools that, for example, they sponsor a city academy. That's putting something back."

He suggested that there are numerous other things schools could do to earn their charitable status. Indeed, he cited a willingness to accept children from disadvantaged backgrounds as just one example.

Charitable status allows schools to pay substantially lower business rates and avoid some tax payments.

Additionally, independent schools are not able to reclaim VAT on premises and teaching materials, which is not the case for regular state schools.

In May, deputy prime minister Nick Clegg argued that increased levels of social mobility could help to stimulate the UK economy, which recently slipped into a double-dip recession.

Mr Clegg, the Liberal Democrat leader, claimed that neglecting the talents of people from disadvantaged backgrounds was an "economic crime", not just a morale one.

Britain must become a "more dynamic society: one where what matters most is the person you become, not the person you were born", he said.

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