Schools should be able to abandon GCSEs completely if they wish to, the head of the government's examinations watchdog has suggested.

Ken Boston of the Qualifications and Curriculum Authority said headteachers should decide whether teenagers sit any GCSEs or move instead to taking AS exams as part of A Level courses.

Boston told the Times that pupils now take too many exams between the ages of 16 and 18.

"If a school wants to offer only a few GCSEs or not take them at all and go straight to A Level and AS then that is perfectly open to them," he said.

The comments have been viewed as raising doubts about the future of the GCSE examination.

But the government has insisted that the exams "continue to prove their worth".

Schools minister David Miliband argued the issue was one for the Tomlinson review of academic qualifications.

"We believe the GCSE is a good exam and any reform must build on it and on its successes," he said.

"Our priority at the moment is stability in the system so that young people, parents and teachers have confidence in the system that is properly organised and they can bask in praise for their achievement, which is what we are going to be focusing on."

The future of A Levels is also under a cloud, with reports that a repeat of last year's results exam results fiasco could hasten the arrival of a baccalaureate system.

Meanwhile, the Conservatives have pledged to make the QCA independent in order to prevent political interference in A Level examinations.