CCEA said it was a small minority of pupils

Around 200 A-Level grades were also changed.

The papers in question were administered by the Council for the Curriculum, Examinations and Assessment (CCEA).

The body said the upgrades represented 0.49% of the 177,624 grades which it awarded in 2007.

Overall, almost 22,000 GCSE and A-level grades in England, Wales and Northern Ireland were changed, and a watchdog has said exam boards should do better.

Ken Boston, chief executive of the Qualifications and Curriculum Authority, which published the overall figures, said: "The number of changes is low, and the review process has ensured that each student has now received the correct mark.

The marking of CCEA examination papers is a thorough and rigorous process which is carried out to the highest standards by trained examiners CCEA statement

"However, it is clear that awarding bodies must do further work to improve their quality assurance procedures and we will continue to monitor their processes."

In a statement, the CCEA said the vast majority of candidates each year are satisfied with their grades.

"The marking of CCEA examination papers is a thorough and rigorous process which is carried out to the highest standards by trained examiners," it said.

"Schools and candidates now have access to scripts, marks and grade boundaries.

"They can therefore make more informed decisions as to whether or not a re-mark is appropriate."