David Hargreaves: Departure disappoints the QCA's chairman

Mr Hargreaves, who will stay in post until the end of this year, said it was time for a younger person to take over the challenge.

The QCA, which holds responsibility for exam standards and integrity, was not making any further comment.

Mr Hargreaves took up the job in September 2000, replacing Nick Tate.

AS-level 'shambles'

He was in post as the first round of AS-level exams - which were widely criticised by teachers, parents and pupils as a 'shambles' - were sat by thousands of students this summer.

I'm very worried that David Hargreaves should be leaving before we see the 14-19 curriculum document

David Hart, NAHT

The Education Secretary, Estelle Morris, asked him to undertake a review of the new qualification and its implementation, following the concerns raised.

Mr Hargreaves has recommended cutting the number of papers sat by candidates.

"Much of my work has been with the secretary of state and ministers, and with officials in the Department for Education and Skills, with whom I have enjoyed the most harmonious of relationships," he said.

"I am confident my successor will build on these and other partnerships."

Post-14 education

But the National Association of Head Teachers expressed concerns he was leaving because the government had prevented him examining the option of scrapping GCSEs in the review of 14-19 education promised in this month's White Paper.

NAHT general secretary, David Hart, said: "I'm very worried that David Hargreaves should be leaving before we see the 14-19 curriculum document."

He hoped Mr Hargreaves's resignation was not down to the government telling him there were some options he could not put forward for debate.

"I'm particularly worried that he has been told that under no circumstances must he put forward the abolition of the GCSE as a potential solution.

"I very much fear that although the government says it wants an open debate it has already made its mind up on some of the key issues over the future of the GCSE," said Mr Hart.

'Significant contribution'

Ms Morris said Mr Hargreaves had made a significant contribution to the government's drive to raise school standards.

"At the Qualifications and Curriculum Authority he has overseen the most complex changes to the exam system for 50 years and his initial review of the new AS levels in the summer has ensured that next summer students will have a streamlined exam timetable," Ms Morris said.

He had been at the forefront of developing a new range of vocational qualifications for young people, she added.

Sir William Stubbs, chairman of the QCA, said: "David Hargreaves's departure will be a disappointment as he has proved to be an effective leader at the QCA."

"In particular, he has stimulated thinking on 14 - 19 matters and revised AS qualifications. He will be sorely missed," said Sir William.

Mr Hargreaves is the second high-profile education figure to resign in recent weeks.

Last month, John Randall, chief executive of the Quality Assurance Agency responsible for scrutinising universities, left in protest at attempts by elite institutions to reduce the amount of inspection they had to undergo.