Cambridge University has dealt a severe blow to government plans to kill off A-levels in their current form, warning it is "worried" about the change and giving strong backing to the present system.
Proposals by Education Secretary Michael Gove to make the exams more traditional and encourage schools to abandon AS-levels have been rebuffed by the Cambridge colleges.
The move would set back a decade-long effort by the university to make admissions fairer and to admit more state school pupils, the university has warned in a letter to Mr Gove, seen by The TES. Oxford University has also issued a robust defence of A-levels, saying they are "helpful" in the admissions process.
The comments are the latest setback for Mr Gove, who has faced criticism for repeated errors over the demise of Building Schools for the Future and the speed with which legislation on academies is being passed.
They follow the news that many top independent schools, including Harrow, also favour the modular ASA level system.
In the letter, Geoff Parks, director of admissions at Cambridge, warns that "admissions tutors in Cambridge have read with interest and a degree of anxiety the reports of your recent comments about A-level reform".
Mr Parks describes AS-levels as an "invaluable indicator of progress" that help decide admissions when many applicants are predicted top grades.
The letter, sent to Mr Gove and his ministerial education colleagues David Willetts, Nick Gibb, Sarah Teather, and copied to Work and Pensions Secretary Iain Duncan Smith, says: "We are worried . that if AS-level disappears, we will lose many of the gains in terms of fair admissions and widening participation that we have made in the last decade."
Mr Gove outlined the shake-up of A-levels earlier this month, saying he wanted the exam to become more academically rigorous and to revive "the art of deep thought".
The Education Secretary had hoped that universities would lead the move away from the modular A-levels, basing his plans on the Pre-U, a qualification offered by Cambridge University's exam board.
But Mr Parks said that in recent years the university has used sixth- formers' AS grades as a central part of its admissions process.
The letter says that the grades obtained by students provide a better guide to pupils' future performance as Cambridge undergraduates than other methods of selection, such as GCSE results - which were "nowhere near as reliable" - or aptitude tests.
Dr Parks adds that the proportion of Cambridge places awarded to students from the state sector and other "under-represented groups" had risen in recent years.
"We are convinced that a large part of this success derives from the confidence engendered in students from `non-traditional' backgrounds when they achieve high examination grades at the end of year 12," he writes.
The letter concedes that admissions tutors are concerned about some aspects of current A-levels, including lack of academic content in some subjects.
It suggests that ministers should consider scrapping the exam sessions that occur for AS and A-levels in January of years 12 and 13. "This would preserve a larger part of the year for learning and intellectual development," says the letter.
Under Mr Gove's plans exam boards would still be able to offer the ASA2 combination, but Mr Gove believes schools will abandon these exams if it is clear they do not meet university requirements.
Mike Nicholson, director of Undergraduate Admissions at Oxford, said: "We still believe that AS-levels can have a role to play in the admissions process.
"While we are not as dependent as other universities in using AS-levels as a differentiator, there are particular circumstances where having assessment after one year of a qualification can be helpful."
A spokesman for the Department for Education said: "It's clear that we need to restore confidence in public exams. We're listening carefully to universities, employers and academic subject bodies' views to ensure A- levels are rigorous and equip young people for higher education."
"We will look in detail at exam structure, including whether schools and colleges should be able to offer traditional two-year A-levels alongside or instead of modular A-levels. We will set out detailed next steps later this year."