The government's policy of greater private sector involvement in education provision has come under fire from a leading teachers' union.

In a policy paper published on Friday, the Secondary Heads' Association argued that ministers were "wedded" to the notion that private companies are better at rescuing failing schools than the public sector.

Instead, the union called for the creation of "school improvement partnerships" of 10 secondary schools, which would swap ideas and best practice suggestions.

Since 1997, a number of local education authorities (LEAs) have been taken over by private firms, but such partnerships have had mixed results.

"The private sector has a poor record of turning round LEAs and schools in difficulties," said SHA general secretary John Dunford.

"By contrast, the less hyped approach using public sector expertise has proved successful many times in recent years."

However, the Department for Education and Skills defended the current approach.

"There is clear evidence that the government's approach of using a range of solutions to tackle deep-rooted problems in failing LEAs is leading to real improvements," said a spokeswoman.

"Ofsted's latest inspection reports on LEAs such as Islington and Haringey find significant improvements following private sector intervention.

"We agree that there are many successful school leaders who can be identified to help schools in difficulties but the work of independent consultants is producing good results where a LEA or school does not have the required capacity or sufficient expertise."