Proposals by David Willetts to revamp the university admission points system in favour of "traditional" subjects would be unworkable, the head of the Universities and Colleges Admissions Service has said.
Speaking after the publication of A-level results last week, the universities minister said he wanted pupils taking subjects such as modern languages and maths to take priority in the race for university places.
Calling for a points premium for some subjects, he said the existing system "sends a very bad message to young people by implying that all A levels have an equal chance of helping them into university".
He added: "(Ucas) is operating a massive system with more than half a million applications, but they need to signal the importance of some A levels more than others."
However, Mary Curnock Cook, chief executive of Ucas, dismissed the idea as too complicated.
"It is hard enough to design a qualification equivalence system at the moment," she told Times Higher Education. "If you started to take into account different currencies for tens of thousands of different courses, it would be just unworkable."
Despite fevered press predictions, Ms Curnock Cook said, a chaotic last-minute scramble for places before the tuition fee cap is raised in 2012 had not materialised. "It has been disproportionately hyped up - I don't see the evidence for that."
She also believed that the hype had caused a record number of students to visit Ucas' Track website to see if they had been accepted by their preferred institutions, causing the site to crash. "People were using it as an early A-level results service - we had 664 hits a second, four times the rate last year."
Encouraging more students to pick up their results at school, where careers advice is available, may be considered in a review, she added.
Although the number of undergraduate places available via clearing fell this year to 39,500 from 47,000, the normal application process accepted 7,500 extra students to take in a total of 402,000.
A record 220,000 applicants would remain unplaced, Ms Curnock Cook said, but about half of these had either turned down places or withdrawn applications.
She also said that better admissions advice was needed. In 40 per cent of cases, the required tariffs for applicants' insurance offers were either equal to or higher than those in the offers made by their first-choice institutions, leaving them unplaced if they did not meet their predicted grades.