Private schools are interested in running city academies - set up to improve the education of state pupils in urban areas - the government has announced.

Schools standards minister David Miliband said he had written to 70 or 80 independent institutions and had received "encouraging" responses.

City academies, an idea Labour inherited from the Conservatives, are usually intended to replace one or more failing inner city comprehensives.

But critics say they will help the best state sector pupils, while ignoring others.

Co-operation

Under the scheme, private sponsors put up 20% of the start-up costs to a maximum of �2m, with the rest coming from taxpayers.

Sponsors run the academies, while the state pays the costs.

David Miliband wants to "expand horizons" for pupils

There are already 180 academies, set up over the last five years. Most of these are sponsored by businesses or the Church of England.

Last October, Mr Miliband asked private schools to become sponsors, saying the idea of an "Eton academy" sounded good.

The government has consistently called for more co-operation between the independent and state sectors.

Earlier this week, Education Secretary Charles Clarke announced private schools could bid for grants of up to �60,000 to share their expertise.

Not poaching

He disclosed that none had pledged to sponsor an academy since Mr Miliband issued his invitation.

But Mr Miliband hinted an announcement might be near, once the exercise was "fully baked".

His comments came after he announced a �1.85m increase in funding for partnerships between state and private schools.

Up to 80 more will be funded over the next three years.

Mr Miliband insisted it was a "two-way street", rather than one sector doing the other a favour.

He added: "This is less about poaching pupils or swapping or joining pupils than it is about expanding horizons of pupils, wherever they are, for the whole of each school, not just for individual pupils from each school."

An Independent Schools Council spokesman said: "This clearly signals that partnership between the sectors is entering a new and stronger phase."