Two-thirds of the city academies built so far have suffered cost overruns averaging £3m, according to a National Audit Office report.

The report into the academies programme said that they have cost and average of £24m, or £27m for new-build schemes. This makes them more expensive than other secondary schools.

The report said that because the programme was at an early stage, its full impact would not be known for several years; however, it said most academies were making encouraging progress in improving the quality of education.