A group of Bradford College A-level students face losing hard-earned university places because part of their exam papers have been lost.

The 33 psychology students were shocked to find the words "No result" for an exam accounting for 40 per cent of their final year mark when they opened their result slips.

The exam board, which has started an investigation into how the papers have been lost, has had to give them grades based on their first year's work.

But the students say their performance would have markedly improved since then and they are losing vital grades because of someone else's incompetence.

Joanna Amato, a single mum, of Buttershaw, Bradford, had studied hard to improve on her first year when she narrowly missed out on an A and fully expected to hit the top mark this time round.

She said that psychology was such a competitive subject that the B she had been awarded could make all the difference between going to a mediocre rather than a good university.

"Some students were at D grade last year but had improved to an A grade this year but all that has been lost," she said.

"I still feel tearful about this because we have all worked so hard for good grades and sacrificed so much. But for what? For nothing."

Alwyn Hockley, of Allerton, Bradford, was awarded a C instead of the B she was expecting and said that everybody on the course ended up with identical grades to their first year.

"I am enormously disappointed about this," she said. "There are a lot of youngsters on the course wanting to go to university who have not got the grades they deserve. Something needs to be done to find out what went wrong. This should never happen again."

The Oxford Cambridge and RSA Examinations (OCR) said today that the 33 papers were among 100 that were lost from six schools and colleges across the Midlands and north of England.

OCR head of policy, Simon Sharp, said: "We will certainly apologise but we are still investigating where the scripts have gone.

"In these cases we grade students on the basis of their other exams because we assume that is what they would have got in the exams they did take. Unfortunately a few scripts go missing every year."

Mr Sharp said that an inquiry into individual students' results would begin if the schools and colleges contacted the board to say that the results did not accurately reflect the grades they should have got. He said that Bradford College had yet not been in touch.

Bradford College director of academic programmes, Gordon Lakin, said: "We will be investigating in detail to find out what the circumstances are and if there is a need to appeal on the students' behalf then we will."