Academies are significantly more likely than other secondaries to use vocational and other non-GCSE qualifications that boost their league table positions, new Government figures reveal.
Among the most popular alternatives being turned to by schools are vocational ICT qualifications, judged of "doubtful value" by Ofsted, which can be worth multiple GCSEs.
The statistics come as the UK's biggest exam board called on Ofqual, the qualifications watchdog, to investigate whether non-GCSEs deserve the value given to them in league tables (see story below).
The coalition Government has justified its academy expansion by stating that average academy exam performance is increasing at twice the rate of other secondaries.
But the Department for Education (DfE) statistics from 2009 highlight for the first time the impact of non-GCSEs on the proportion of pupils achieving the benchmark of five A*-C grades, including English and maths.
The difference in results when non-GCSEs are removed from the score in 12 state schools, including three academies, is more than 20 percentage points (see box below). This means academies were eight times more likely than other state secondaries to improve their league table standings in this way.
Academies made up only 4 per cent of state-funded secondaries in last year's GCSE league tables.
Many schools argue they need alternatives to GCSEs to keep all pupils engaged with an education that suits their individual needs.
But Anastasia de Waal, education director of think tank Civitas, who has researched the qualifications offered by academies, said many are using "highly questionable" and "pseudo-vocational" courses.
"These new figures show academies are turning to soft options to boost their results, which is very worrying since the academy model is being used as the flagship model of improvement," she said.
"It is particularly concerning when it is being championed by a coalition led by Conservatives who have repeatedly and consistently said that a full academic curriculum is a must for all pupils."
The Conservatives last year proposed removing vocational qualifications from league tables because they were "far less academically demanding" than traditional GCSEs.
Nearly two-thirds of all state secondaries and 86 per cent of academies offered at least one non-GCSE course that counts towards their league table score, according to the DfE statistics.
The TES identified 116 schools where the GCSE benchmark score dropped by at least 10 percentage points when non-GCSE qualifications were removed. Twelve per cent of academies are represented in this group, compared with only 3.4 per cent of other state secondaries.
Mike Butler, Independent Academies Association chairman, representing around 100 academies, said: "It is important that vocational qualifications are not excluded from Government league tables.
"Vocational qualifications can be an important incentive for students, particularly in disadvantaged areas, to achieve, not only in those vocational subjects but in subjects such as English and maths."
Nick Gibb, schools minister, said: "It is very important that young people are entered for the qualifications that are in their best interests rather than being entered for exams simply to boost the league table position of the school.
"We are going to radically reform league tables so parents have completely transparent information about exam performance."
`NO APOLOGIES' FOR HANDS-ON FOCUS AT NATION'S `MOST IMPROVED'
Barnfield West Academy was named the country's most improved academy by the Specialist Schools and Academies Trust in March. In 2009, the Luton school achieved a perfect 100 per cent of pupils gaining at least five A*- C GCSEs or equivalent.
At 54 per cent, the proportion that also achieved English and maths GCSEs was impressive for a school where free school meals are more than twice the national average.
New Government figures show that score falls to 29 per cent when only GCSEs are included and that much of the academy's achievement is with "vocational" and other non-GCSE qualifications.
But Andy Hardy, acting principal, makes no apology for his school, judged "outstanding" by Ofsted, offering what he says is a "truly personalised" curriculum.
All pupils take GCSE maths and English, with the proportion achieving a C or above in English going up from a third to two-thirds compared with its predecessor school.
The OCR national level 2 in ICT, worth up to four GCSEs in the league tables, is also compulsory. Ofsted has said the qualification is of "doubtful value" and teaches pupils what they already know.
But Mr Hardy describes the work and engagement it produces in pupils as "exceptional".
- Original headline: Academies veer towards vocational courses despite doubts over worth