The most able A-level students will be encouraged to sit a new S-level paper by 2000 if universities approve proposals out next week.
The revamped S level will replace the "special" A-level paper, which has become less popular in the past ten years. Critics say that the extra coaching required to pass the paper discriminates against state school pupils. University admission tutors are also sceptical about whether special papers gauge academic ability.
But with more grade As at A level there is a need to differentiate between candidates. The S level is designed to challenge very able students with more difficult questions without requiring any additions to the syllabus.
The Qualifications and Curriculum Authority hopes it will also answer complaints from elite universities that there is a growing gap between the standard of A-level study and that expected in the first year of a degree.
A spokesman said the S level would be based on the same broad subject criteria as is being devised for A and AS level examinations. Questions would require a greater depth of understanding rather than more information.
But Bill Stephenson, maths admissions tutor at University College London, is doubtful the new paper would solve the "very real problem" of differentiating between increasing numbers of grade A applicants.
The elite institutions were turning away very well-qualified students, he said. But another S level exam may not be the answer, since more difficult questions required additional training.
"Sitting another paper, even one like this, still requires students to be differently prepared. This will still give the advantage to better resourced private schools. It may be fairer to differentiate the A grade further using a star system like the GCSE," he said.