A controversial plan to rank all A-level students according to the schools they attend – which would allow universities to discriminate against pupils from private schools – is unveiled today by Britain's biggest exam board.

The radical proposal would allow universities to offer places to students from disadvantaged homes who showed potential but had performed less well in exams than their peers at better schools.

The plan by the exam board AQA (Assessment and Qualifications Alliance) provoked a storm of argument among academics and independent schools. There were immediate fears that candidates will be penalised simply because they achieve good A-level results at a good school. Independent schools are also alarmed that the approach could discriminate against disadvantaged pupils to whom they have offered scholarships.

Dr Tim Hands, headmaster of Magdalen College, Oxford, and co-chairman of the Independent Schools' Universities Committee, said: "It is extraordinary. It takes no account of home background or the amount of tutoring a pupil could have."

Professor Alan Smithers, head of the Centre for Education and Employment Studies at the University of Buckingham, added: "There must be concerns about the ranking the candidates are awarded. The possibility for errors is enormous." The plan is contained in a paper prepared for discussion by Dr Neil Stringer, senior research associate at the AQA Centre for Education Research and Policy, and being circulated at the party conferences for debate this month.

It advocates the drawing up of a national system for ranking both candidates’ achievements and the educational context in which they were taught.

Pupils at weak schools would get bonus points; those at elite schools could be penalised in comparison.

Dr Stringer cites the example of St George’s Medical School in London in support of his argument. It offers places to students with lower A-level grades (BBC rather than AAB) providing that their performance is 60 per cent better than the average for their school.

“St George’s reports that students from poorly performing schools who are accepted into medical school with lower grades do just as well as their peers with higher grades,” he adds.

“This strongly suggests that students admitted through the adjusted criteria scheme learned enough at A-level and are able enough learners to compete successfully with students who achieved higher A-level grades under more favourable.”

Under the blueprint he has devised, students would be awarded an exam score based on their best three A-level grades and then placed into different performance bands. They would then be given the ranking for their school.

Dr Stringer says the system could either be offered to universities individually – or drawn up centrally by an existing agency like Ucas, which is currently reviewing its A-level system.

The AQA believes it can be an an alternative to allowing students to apply to university after they have got their results – rather than be awarded places on predicted grades. This plan, under active consideration from ministers and said by some to be fairer towards disadvantaged students, has failed so far to get off the ground largely because of opposition from universities.

Professor Smithers added: “I would hope that any university worth its salt would look at the candidates’ achievement and inform their own view as to their potential.”

Dr Hands added: “Cambridge University, which features at the top of many a global league table, has recently published research that shows prior schooling is of insignificant effect with regard to degree outcome.

“The proposer of this scheme might like to bear this in mind.”

Brian Lightman, general secretary of the Association of School and College Leaders, which represents the majority of state secondary school heads, described it as “a step too far”. He said it should not detract from the need to provide all pupils with a good education in a good school.

Lee Elliott Major, of the education charity the Sutton Trust, which campaigns to get more disadvantaged young people into leading universities, said: “We support the use of so called contextual information when judging students’ potential and achievement.”

However, he added that the “bigger challenges” were in getting “more children with the grades at school to make university a realistic prospect and encouraging pupils to actually apply when they have the grades”.

Dr Stringer stresses in his paper: “The proposed system would not encourage or require universities to relinquish control of their admissions systems. It is not an issue of allocating students to universities on the basis of their respective rankings: admissions tutors would be free to make decisions.”

The AQA said the scheme could be considered as an alternative to Post Qualification Application – allowing students to apply to university after getting their results.

That, argued Andrew Hall, chief executive of AQA, would lead to a shorter teaching year if exams were brought forward.

“We have real concerns about the effect this could have on the performance of some students,” he added.

“So our Centre for Education Research and Policy have devised a different way to tackle the issue that doesn’t disadvantage any student and allows all applicants – from whatever their school type or background – to compete fairly for university places.”

* Meanwhile, plans to mark GCSE students on their spelling and punctuation and scrap most resits were published by Ofqual, the exam standards watchdog, yesterday.

It has launched a consultation on the proposals which would see teenagers – from 2012 – having to sit all their exams in the summer at the end of two-year courses rather than sit modules throughout the course.

They would also only be allowed to resit English and maths.

The reforms were first announced by Education secretary Michael Gove earlier this summer.

How the new system would work

Under the new system, a pupil at a weak school who got a lower grade than a rival pupil at a good school could still be given more university entrance points, writes Richard Garner.

The blueprint would work like this. James goes to a low-performing comprehensive in a disadvantaged area. He manages to get an exam score of 36 out of 40. However, he is entitled to bonus points as a result of his school's low ranking (it scores minus three in the rankings).

Adam, on the other hand, goes to a top performing independent school with no pupils on free school meals and got 38 for his exams. But he faces being penalised on his school's ranking (the school is given a "plus three" ranking).

It would, of course, be up to the individual university to decide what to do with this information but one way of using it will be to add three points to James's exam score because of the background he comes from and deduct three points from Adam. On that basis, the place would go to James.

The argument in the paper is that there are still vastly more points awarded for exam performance than education context and it is unlikely that any university would be as crude as to deduct the maximum ranking points from Adam and give the maximum three extra to James.