Teachers could be left unable to make anonymous complaints about exam papers after the future of an independent grievance system was called into doubt.
The Association of Teachers and Lecturers (ATL) has told members it is pulling out of the three standing joint committees (SJCs), which report teacher complaints to the boards, claiming that they are "overly bureaucratic".
Other unions, which are also scaling back the number of representatives they have on the committees, are also considering whether to continue their participation.
The Association of School and College Leaders will be hosting a meeting of unions to discuss the future of the SJCs later this month.
The ATL said it was withdrawing its support for the committee system because it was overly bureaucratic, considering the small number of complaints it received from members about papers.
It also said that the system had been devised before the existence of exams watchdog Ofqual and was unsuited to the new trend for exams spread throughout the year.
But one member of the committees, who was angered by the ATL's decision, contacted The TES to say: "This has wider repercussions that if members wish to comment on any examination procedure or paper that is taken by their students, they have no way to do that.
"Surely this is removing empowerment from the members of the association and leaving it to become a dictatorship? It is letting the examining bodies put into the specifications and examination papers what they wish to and not allowing those who prepare candidates for examinations any redress if there is a problem or complaint," they said.
But ATL head of education policy and research Nansi Ellis said: "Members can still complain through our website and our department will take any issues forward. Last year, the committees covering the OCR, AQA and Edexcel exam boards only got around 150 comments altogether across all the exams they set.
"For this small number, there have to be a lot of meetings of the committees, then meetings with the boards. It has become overly bureaucratic for the number of complaints."
Headteachers gave a mixed reaction to the work of the committees. Martin Burgess, headteacher at Shuttleworth College in Burnley, Lancashire, said: "Accountability and proper scrutiny are better done by independent bodies than bodies with vested interests.
"Exam boards look like they are becoming more independent, not less, so we need a system of accountability like the SJCs. I would be very concerned if they disappeared altogether."
But Simon Dennis, headteacher of Hockerill Anglo-European College in Bishop's Stortford, Hertfordshire, said: "If there are any problems now, we do our own analysis and if we think there is a problem, we take it directly to the exam board. So far, they have been pretty responsive."
A NASUWT spokesman said it was currently "engaging with representatives" about the issue.
Steve Iredale, chair of the curriculum and assessment committee at heads' union the NAHT, said the association was "reviewing its position".
However, NUT general secretary Christine Blower said: "The NUT continues to believe that the work of the SJCs is crucial in representing the independent views of teachers. These views provide an important commentary on and contribute to the improvement of examinations."
ON REPORT - Marked down
Comments from the standing joint committee report on OCR exams 2010:
- GCSE technology
"Could OCR please state on the front of the question papers and in the stationery list that calculators are allowed? It would remove the need for centres to telephone the awarding body for clarification."
- GCSE gateway triple science
"Concern was expressed that that the exams in these subjects were too easy ... The exams were described as 'nothing more than a joke' and 'becoming worthless'."
- 21st century science: additional science
"Concerns have been raised that a significantly high number of candidates complained to science teachers that there was not enough time to finish the examination paper."