Education Secretary Michael Gove's A-level reforms are in danger of wrecking government plans to persuade more disadvantaged students to go to university, the head of the admissions service has said.
Mary Curnock Cook, chief executive of Ucas, told a conference on Thursday they could have a "detrimental" effect on the number of young people from poorer homes studying academic qualifications.
She cited evidence which showed that a growing number of students in state schools were already shunning A-levels and leaning towards studying for a vocational qualifications.
In addition, while independent schools still virtually shunned vocational qualifications - only 1.1 per cent of their pupils taking them the figure for state schools was 37.9 per cent. There had been a fivefold-growth since 2004.
"We all know about new tougher, more rigorous A-levels and these indeed might be desirable in themselves but I can't help anticipating that a public understanding that A-levels are getting more difficult is likely to increase this big trend towards vocational qualifications that we've seen," she said.
"Given that greater propensity for those from lower socio-economic backgrounds to do vocational qualifications, I believe this might well have a detrimental effect on some of these positive trends we've seen we've seen recently in widening participation and fair access (to universities)."
Figures showed the gap between those from poorer homes and the better off going to university had fallen in recent years. Richer pupils were now 2.8 per cent more likely to go compared with 3.2 per cent two years ago. However, they were still 7.2 per cent more likely to get into a Russell Group university (the group represents 24 of the most selective higher education institutions in the country).
The figures also showed that - whereas 85 per cent of independent school pupils applying to higher education made applications to the more selective universities this year - the figure for state schools was 48 per cent. On acceptances, the respective figures were 69.6 per cent and 42.4 per cent.
She pit forward two reasons for this: on average non-selective state school pupils were three whole grades lower than independent and grammar schools in their A-level results.
In addition, only 53.2 per cent of state school pupils had studied the so-called "facilitating subjects" accepted by the most selective universities - compared to 72.4 per cent of independent school pupils.
"I think it's quite clear that higher-tariff institutions want to recruit those with academic qualifications such as A-levels," Ms Curnock Cook added.
"I think it's worth thinking about - if you have a done a BTEC in health and social care, you are very likely to progress on to a course in higher education in health and social care whereas if you've got three A-levels, you've got a choice of probably literally thousands of different courses to choose from. So it's also a narrower progression route."
She said that schools were extremely "patchy" in the advice the gave to pupils over subject choices at A-level.
"Some schools are pushing young people into choices that help schools get their performance measures (i.e A-levels considered less hard)rather than doing the best thing for those young people," she said. However, she conceded this could change with the scrapping of the five A* to C grades at GCSE including maths and English performance measure.
Ms Curnock Cook also drew attention to the growing disparity between the number of men and women applying for university places - 48 per cent of women were doing so compared to 37 per cent of men.
"Women are a third more likely to apply to higher education," she said. "In fact, the situation has got so bad that there are more women in higher education than men applying."
Under Mr Gove's A-level reforms, students will no longer take modular exams throughout the year but face an end of two year test of their knowledge instead. Questions will be sharper aimed at encouraging pupils to show thinking skills. The new qualifications are due to be introduced in September 2015. Ministers have insisted the reforms are necessary to prevent grade inflation and ensure A-levels keep their world-class status.
Meanwhile, latest figures from Ucas show applications for university next summer are more than 4,000 down on the equivalent figure for last year. Figures show there have been 140,890 applications - compared to 144, 980 this time last year.
A spokeswoman for the Department for Education said: "It is simply wrong to suggest that disadvantaged pupils cannot cope with academic rigour.
"The success of the English Baccalaureate proves that children from all backgrounds can achieve success in academic subjects.
"It does children no favour at all to dumb down exams while their peers in other countries are meeting ever higher expectations."Reuse content