Universities are failing to "value or even understand" the International Baccalaureate Diploma Programme (IB) and prospective students taking the qualification are being unfairly treated as a result, two leading school heads have said.
Anthony Seldon, master of independent school Wellington College, and John Oakes, head teacher of Dartford Grammar School, a state school, said they were "constantly surprised" at the "unreasonably high" offers being made to students taking the alternative to A levels.
Writing in this week's Times Higher Education, they say there is a failure among university staff to appreciate how "intrinsically challenging" the IB courses are compared with A levels.
The IB diploma, the students of which take a broader range of subjects than is standard practice at A level, has been held up by some politicians and experts over the past 10 years as a better model for post-16 education.
Dr Seldon and Mr Oakes say that recent research by the Higher Education Statistics Agency, carried out on behalf of the International Baccalaureate Organisation, shows "compelling evidence" that those taking the IB are more likely to go on to achieve first-class honours degrees at university.
"Universities in the UK should be trumpeting the IB diploma," they write. "Our experience, however, is that not all of them value or even understand it. University staff all too rarely visit schools beyond 'introduction to higher education' events and talks. Thus, they do not appreciate quite how hard the IB students work over two years; nor do they really grasp how much more intrinsically challenging the courses are than A levels."
In particular, they protest that students are being asked for the highest grades at IB, which are more difficult to achieve than "As" at A level.
Matthew Andrews, chair of the Admissions Practitioner Group at the Academic Registrars Council, said university staff were "very familiar" with the IB and gave it a "lot of respect".
Many of the admissions issues surrounding the diploma had been investigated during the Universities and Colleges Admissions Service's "robust process" for incorporating IB into its tariff framework, he added.
"The schools that teach it often feel that their students are not getting proper credit - and that is the bit that universities don't necessarily agree with," he said. "It is in the interest of schools that teach IB to promote its benefits, but I think those that offer A levels would say that they can teach many of the same things."