Almost one in four sponsored academies were judged inadequate, or fell below the minimum standard for exam results, within two years of opening, new figures show.
According to data for August 2015, 340 sponsored academies - usually under-performing schools taken over by an outside sponsor to turn them around - were in this situation. This represented 24 per cent of all sponsored academies.
The figures are contained in the Academies Annual Report for 2014-15, published by the Department for Education today.
The problem was particularly acute in the North England region, affecting 43 per cent of sponsored academies - 26 in total.
The North-East London and East England region had the lowest proportion, at 15 per cent.
The report also showed that 4 per cent of converter academies, usually highly-performing schools that decided to move away from the local authority, were in the same situation within two years of changing their status.
The annual report covers the full first year of the regional schools commissioners (RSC) system, where eight RSCs oversee academies and free schools in eight regions of England.
It shows they issued 43 pre-warning notices to academies in 2014-15: 13 to converter academies, 28 to sponsored academies, and two to trusts concerning four academies.
They issued a further seven warning notices, all of which went to secondary academies.
In the same period, the growth of 14 academy sponsors was put on hold because of concerns about either their finances, leadership or educational impact.
The year also saw the Department for Education move 29 sponsored academies to new sponsors - 22 secondary schools, five primary schools and two special schools - while 25 converter academies were put into a multi-academy trust - 10 primaries and 15 secondary schools.
The annual report also showed that the Education Funding Agency issued 15 financial notices to improve to academies between August 2014 and July 2015.
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