Even students with A grades are trying to improve their marks as the competition for places at the best universities intensifies. One grammar school in the South-east, which charges students pound;15 per resit, collected Pounds 5,000 last summer, the equivalent of more than one retake for each sixth-former.

New rules introduced two years ago after the A-level grading fiasco allow pupils to retake papers as many times as they want. This can pay dividends as A-level grades reflect the average percentage score in several AS and A2 modules. Heads now want the loophole to be closed, saying it has made a mockery of the exam process. They spoke out as an estimated 265,257 pupils await their A-level results next week.

Students have already been warned that they face the stiffest competition yet to make it into the university of their choice this year. The trend of improving A-level results year-on-year, coupled with the introduction of student top-up fees from September next year, has led to a record 8 per cent surge in applications this year.

Martin Ward, deputy general secretary of the Secondary Heads Association, said: “Young people clearly understand their subject better in the second year of an A-level course, so it is not surprising so many are choosing to retake the first-year exam again. AS-level results should not contribute towards the final A-level grade for precisely this reason.”

Exam boards are unable to give figures on the number of retakes. However, figures from the AQA and OCR boards show that the number of papers taken in January 2005, an examination session when many pupils resit AS modules, rose 11 per cent from 994,162 in 2004 to 1,104,041.

One exams officer at an east Midlands school said: “We have loads of kids resitting modules - even those with A grades - because it will give them a better chance of getting into a university such as Cambridge.

“We get the weaker students, who have not done as much work as they should, resitting. Then the cleverer ones, who want to apply for the better universities, are also resitting.

“They accept the original mark, but know that if they can improve the second time they take the paper, that will raise their overall A-level marks.”

Jamie Mitchell, 18, resat an AS-level physics module at Lutterworth grammar, Leicestershire, in January and improved from a C to an A grade. “I was not happy with my results first time around and felt I hadn’t put enough effort in,” he said.

Critics, including the right-wing think-tank Politeia, opposed unlimited resits, saying they would lead to grade inflation, the charge which led to the regrading controversy three years ago.

At Colne community school, Colchester, the number of students resitting papers has risen from 10 in 2004 to 22 this year, among a sixth form of 250.

Terry Creissen, the head, said: “People who fail to make the grade by a few marks and resit are making a conscious decision that they do not want to go to their second-choice university. It is perfectly understandable.”

One in three sixth-formers at South Dartmoor community college, Devon, has retaken at least one AS or A-level module this year. The figure is slightly up on 2004. Ray Tarleton, head, said: “There is pressure on sixth-formers throughout A-level courses now. The retakes are a reflection of that.”

* warwick.mansell@tes.co.uk