In part it is aimed at recognising the increasing variety of qualifications university applicants have, other than traditional A levels.

But ministers are said to be opposed to the idea because they think it would devalue the highest A level grades.

Tony Higgins: "Need to recognise diversity"

The Universities and Colleges Admissions Service (Ucas) says that at present many 'league tables' assess A level success in terms of points - from 10 points for an A grade down to two points for an E, the lowest pass.

"The current scoring system is crude and does not take account of other qualifications, such as Scottish Highers and Advanced Highers, GNVQ and the new AS exam," Ucas says.

And schools say the present points system is unfair to those who get lower grades, because it makes an A worth five times as much as an E, yet candidates need as much as 44% of the marks to get an E and as little as 70% to get an A.

"The present A level points system was introduced by our predecessor, UCCA, as an internal reporting mechanism well over 30 years ago," said Ucas's Chief Executive, Tony Higgins. "It was never meant to be used for the allocation of places to students or the construction of league tables.

Various options

"Since then there has been an explosion in the number of people going on to higher education, and many of them now have very different types of qualification and achievement.

"We need a new tariff to recognise that diversity."

Ucas is seeking views on a range of alternatives. One option might be to change the points ratio between A and E grades to two to one or three to one.

Another approach might be to have a different range of points, such as giving an A grade 120 points, or 36 or 12, and scoring the lower grades proportionately.

In an effort to head off criticism, Mr Higgins stressed that there would not be any change to the way A levels are marked and it would not change the value of the grades themselves.

Ministers 'oppose change'

"It will make it neither easier nor more difficult to get a place in higher education. Entry standards will remain as they are," he said.

Traditionalists claim it will inflate the achievement of candidates with poor grades, however.

Dr Sheila Lawlor, of the right wing think-tank Politeia, said: "This would only make a difference to people who think they can get into university with lower grades."

And a senior government source said ministers feared that the proposals would devalue top grades, and prompt some universities to devise their own admission tests. Ministers believed the relative points score for A and E grades should remain unchanged.

'Disappointing'

"We want pupils to be stretched to achieve their potential, and the relative values of the different grades does matter," the source said.

"If you make an A grade less special, then young people may feel that getting Ds and Es is adequate. "

A spokesman for Cambridge University said the Ucas proposals would make little difference there, because it asked applicants to achieve certain grades, not points.

The General Secretary of the Secondary Heads Association, John Dunford, thought the government's view was "very disappointing and completely wrong".

"The Ucas proposals simply re-adjust the differential between the top and bottom grades from a disproportionate five-to-one to a more realistic position," he said.