An Epsom headteacher has hit out at this year's marking of A-level course work by one examination board which he says has left many students feeling devastated after receiving unexpectedly low grades.

Stephen Borthwick, headmaster at Epsom College, is among dozens of other headteachers from independent schools who have sent examination papers back for re-marking after claiming students exam grades had been manipulated. They accuse the Oxford, Cambridge and RSA board (OCR) of downgrading students' course work to avoid embarrassing questions about falling standards and record numbers of A grades.

Now they have called for a meeting with the examination board to discuss what they claim is exam fixing. Their claims have sparked a national debate over the marking of this year's A-levels.

Mr Borthwick said this year the school had asked for more than one third of its students grades to be remarked. He said alarm bells started to ring at the school that something was not quite right on the day the A Level results came out.

He said: "The marks for their course work components was very much lower than the marks in the other modules and it was much lower than we would have expected."

He added the unexpectedly low grades in the course work modules had cost some students their first choice university place and left many students feeling devastated.

One student had missed out on a place in Cambridge this year because she received a U, a very low fail, for her geography course work.

The student in question scored A grades in her other A-level subjects and every other module of the geography syllabus except course work.

Mr Borthwick said she was one of the worst examples of how the unexpectedly low grades for course work had affected students.

He said: "So far a lot of the requests for remarks have resulted in no change having seen some of the papers we remain surprised at the marks which have been awarded."

He added: "If the parents have no confidence in one of the major examining boards in this country, it will have a major impact on the system of examination."

Head of Epsom College's geography department Peter Irvine said: "What's happened is unprecedented in our exam profile which we have built up over the last 10 to 15 years."

But the chief executive for the examination board Dr Ron McLone denies there has been a fix, claiming pass rates for course work continues to be higher than that of written papers.

A spokesman for OCR said the board will always investigate cases where schools are concerned about the results awarded.

He added: "OCR's prime concern is that its customers are reassured the public examination system is fair and just. OCR is working closely with Qualification and Curriculum Authority to ensure full confidence is restored as soon as possible."

A delegation of headteachers from independent schools was due to meet with OCR representatives yesterday to discuss the issue.