Almost half a million pupils are in academies deemed inadequate or require improvement since converting from council-run schools, according to council chiefs.

The Local Government Association (LGA) claim the new data illustrates the challenge faced by those responsible for the academisation agenda – and the potential risk it poses to children’s education.

Figures revealed 89% of council-maintained schools are rated as good or outstanding, compared to 62% of sponsored academies.

It also shows 45% of sponsored academies are still awaiting their first full Ofsted inspection and in all of the Regional Schools Commissioner (RSC) areas – the body responsible for academies and free schools – council-maintained schools outperform academies across the country.

Only eight RSCs are now responsible for a quarter of schools in England, totaling more than 5,000 academies and free schools, with each body working with around 100 academies rated less than good as well as those still unrated.

The LGA claim it shows ‘a serious lack of capacity and capability within the civil service’ to press ahead with the academy agenda.

Government wants to see all schools become academies by 2022 although issues remain over how to convert remaining institutions, such as how a local authority can be deemed ‘unviable’ in its role for failing schools.

Councils’ legal role in overseeing and improving school standards is also expected to be debated by Parliament next year when the Education for All Bill will be put forward.

Cllr Richard Watts, Chair of the LGA’s Children and Young People Board, said: 'Placing more and more power in the hands of few unelected civil servants, who parents cannot hold to account at the ballot box is out of sync with the Government’s aims to devolve more decision-making and responsibility down to local areas and communities.

'With the Government planning to end councils’ role in supporting school improvement and intervening in failing schools from next year, we have yet to be convinced that RSCs have the track record or the capacity to take on responsibility for another 13,000 schools.'