Proposals over a way to change the exam appeals system could make it completely unfair by making it harder than ever before to appeal against GCSE and A-Level results, head teachers have claimed. 

According to reports, the exams regulator Ofqual wants to make changes that would mean marks only being added to papers in a case where an examiner has been found to have made a mistake, either in the award of a point or the counting up. 

Ofqual said the new system would mean it could focus on eliminating errors in exam marking, but head teachers from two leading organisations have said it makes the process of appealing against a grade much harder than ever before. 

The National Association of Head Teachers (NAHT) and the Headmasters and Headmistresses Conference (HMC) said the proposals are "unpersuasive, misdirected and likely to make the current unsatisfactory situation worse".

Both teacher groups said there are concerns that the new system would mean that there is little leeway when it comes to how someone perceives an answer. Should it all come down to nothing but technical errors, there could be cases in which two examiners disagree over the academic merit of an answer, but only the opinion of the first would be taken into account. 

In a statement, the two groups said there was "deep disappointment" that the exam board has "failed to tackle the key problem of ensuring accurate first-time marks for all candidates".

HMC chairman Chris King said Ofqual's proposals were fundamentally flawed and could put pupils' futures at risk. 

"The approach seems to be: 'We have too many complaints; let's make it harder to complain'," he said. 

"This is no way to restore confidence in fairness and accuracy."

NAHT general secretary Russell Hobby went on to say that pupils should be "entitled to a system that gets the marks right first time and is easy to challenge if something goes awry. 

"Their futures depend on this and their hard work demands it," he added.