England's exams regulator is clamping down on the "unfair advantage" gained by some schools which seek high numbers of GCSE and A-level re-marks.

Ofqual is changing its system this summer, so that new marks can only be issued if a "marking error" is found.

Their research shows independent schools seek twice as many GCSE reviews as comprehensive schools request.

But Chris King, chairman of the independent schools body the HMC, said the system would be less fair.

Most reviews led to slightly higher marks, Ofqual said, penalising pupils from schools which did not ask for re-marks.

It said the change would mean a "level playing field". 

Independent schools sought reviews for one in eight A-level grades, more than twice the proportion of state-funded colleges, it added. 

Exam boards charge fees of between £20 and £60 per paper to be re-marked, but refund the fee if the grade changes. These costs are borne by the school.

'Second bite of the cherry'

Overall more than 90,000 A-level and GCSE results were changed on appeal in 2015 - an increase of 17% in one year and the highest on record.

Julie Swan, Ofqual's executive director for general qualifications, said it was clear from its analysis that the current system could be fairer.

"It is not fair to allow some students to have a second bite of the cherry by giving them a higher mark on review, when the first mark was appropriate," she said.

"This undermines the hard work and professionalism of markers, most of whom are teachers themselves.

"These changes will mean a level playing field for all students and help to improve public confidence in the marking system.

"We want schools to be able to ask for a review if an error has been made. Nothing we are doing will make it any more difficult for a marking error to be corrected."