Ministers, concerned that pupils are being "deceived" into taking courses of "no value", are considering wresting control over which qualifications count in school league tables from the independent watchdog.
In a report welcomed by Government yesterday, Alison Wolf calls for legislation to redraw the responsibilities of the exams regulator Ofqual, which she says has contributed to a system in which too many pupils take "sub-standard" qualifications.
Professor Wolf, who is director of public services policy and management at King's College London, told The TES that asking Ofqual to decide whether individual qualifications were "any good" was not appropriate for an "unelected and unaccountable" agency. "A qualification is not like a can of beans on a shelf," she said. "Qualifications are one of the quintessential ways in which governments implement their policy for schools."
Her report on vocational education outlines an "explosion" in the number of 14-16 "vocationally related courses" with GCSE league table equivalencies taken in schools from 1,882 in 200304 to 462,182 by 2010.
Professor Wolf said Ofqual and its predecessor had played a role in this "transformation", which was "a result of creating a regulatory structure that is not currently fit for purpose".
The "explosion" in vocational courseshad not been "properly discussed in advance", "was not expected by ministers" and "had come about because we have created this incredibly complex overlapping non-transparent set of agencies". "That is not a good way to run an education system," she said.
Some educationalists will oppose the idea of giving politicians a greater role in assessment because they believe it can offer too much temptation to distort the system to suit their own political ends.
Ministers already have formal powers over which qualifications count in league tables but Ofqual has effective control because it must approve them first.
Professor Wolf says the watchdog does not have the expertise to decide if vocational qualifications are of "good quality".
Her report says it is Government that should decide exactly which vocational qualifications count in GCSE league tables, explain to the public why, and limit their worth in accumulated performance measures.
It recommends that schools spend no more than a day a week teaching vocational courses to 14-16 year-olds so that there is enough time for essential core academic subjects.
The report says research does not support widespread claims that vocational courses motivate pupils to achieve better grades in other subjects and stop them becoming Neets.
"The perverse incentives created by performance measures combined with indiscriminate `equivalences' have resulted in large amounts of sub- standard education in which many young people take courses that were in no sense truly `vocational' or useful," it says on 14-16 education in schools.
Post-16, the review reports that between a quarter and a third of sixth formers and students exist on "a diet of low-level qualifications, most of which have little or no labour market value".
Eduation secretary Michael Gove blamed the post-16 problem on "far too many 14-16 year-olds doing courses with little or no value because performance tables incentivise schools to offer these inadequate qualifications".
"These young people are being deceived," he said. "This is not just unacceptable but morally wrong."
Government sources have highlighted courses on "personal effectiveness", "key skills and problem solving" and a "certificate in preparation for working life" when asked which qualifications could have their league table positions removed.
But the most popular "vocational" qualifications of all in schools tend to be in more mainstream subjects like ICT.
Last year The TES revealed that the OCR National level 2 in ICT had become the fourth most popular 14-19 course in English schools, used by more than half of secondaries.
A 669 per cent rise in entries in two years meant it was being taken by more pupils than many GCSEs in maths, English and science.
But Ofqual found the course was too easy and forced OCR to introduce a toughened up version in September.
Schools watchdog Ofsted had already described the course - where tasks include sending an email and searching the internet - as being of "doubtful value".
The Wolf report recommends that schools should still be free to offer any course from a regulated exam board even if it is not approved for the league tables.
Government sources stress that existing courses could be amended to meet new criteria and that major exams boards are aware of the "direction of travel".
REVIEW KEY POINTS - War on `exams without value'
- League table "perverse incentives" to take useless courses have led to "large amounts of sub-standard education".
- Post-16: up to a third of sixth formers and college students exist on "a diet of low-level qualifications, most of which have little or no labour market value".
- Ministers, not Ofqual, to decide which vocational qualifications count in league tables.
- Legislation should be considered to redefine the watchdog's responsibilities.
- No evidence that vocational qualifications for 14-16 year-olds motivate them to succeed in other subjects and prevent them becoming Neets.
- Schools should spend no more than 20 per cent of teaching time at key stage 4 on vocational qualifications.
- Essential general subjects must not be crowded out.
- Work experience should wait until post-16.