The Universities and Colleges Admissions Service has defended its new tariff points system for entry qualifications in the face of a boycott by many Russell Group universities.
The tariff sweeps up all new Curriculum 2000 qualifications, including key skills, into the same points score system as A levels.
Top research universities said it was too complicated and confusing and allowed candidates to increase their score with qualifications that might not normally be accepted.
Scottish institutions have complained that the tariff downgrades Highers and Advanced Highers by comparison with other qualifications.
Tony Higgins, Ucas chief executive, said the tariff was an attempt to "achieve a more realistic relationship between grades, which was manifestly wrong before, and to draw a correct comparison between so-called academic and vocational qualifications throughout the UK for the first time".
Stephen Dudderidge, admissions coordinator for Nottingham University, said the tariff was more useful for new universities than institutions like Nottingham.
"For most of our courses we need to see a clear level of attainment in specific A-level subjects, so the easiest way for us is to stick to the straightforward old system," he said.
Linda Bruce, assistant secretary for undergraduate admissions at Edinburgh University, said Scottish Highers and Advanced Highers "do not come out as well in the tariff as we know they should".She said the system also allowed applicants to build up a reasonable points score without having a broad range of achievements.
Mr Higgins said more than three-quarters of universities and colleges had indicated they intended to use the tariff.