The Conservatives have called for a shake-up of the examination system after it was revealed that the costs of exams have soared by more than Pounds 100 million over five years.
The combined cost of implementing GCSEs, ASA-levels and GNVQs was Pounds 155 million in 200203, but the figure shot up to Pounds 265 million last year.
The figures were revealed last week in the answer to a parliamentary question from Michael Gove, the shadow schools secretary.
Mr Gove said the "huge" increase in costs faced by schools each year should lead to a major overhaul of the exam system.
"Parents and teachers will be shocked to see that the cost of exams is hundreds of millions of pounds a year," he said.
"External assessment is hugely important, but the huge increase in modular testing means children spend more and more of their time sitting bit-part exams and (doing) resits instead of actually learning.
"We want to simplify the exam system so there are fewer modules and more rigour. That's why we've asked Sir Richard Sykes (former rector of Imperial College London) to lead a review of our exam system."
The Liberal Democrats said the actual cost of exams is "considerably higher" than the figures show as schools have to pay invigilators.
David Laws, the party's education spokesman, said: "The astronomical rise in the amount of money being spent on exam fees is putting serious strains on school budgets. We need to review whether the current exam structure is both the best way of testing pupils and whether it offers good value for money."
The Association for School and College Leaders said the continuing rise in exam costs is an issue that the secondary headteachers' and college principals' union has been fighting for "many years".
John Dunford, the general secretary, told The TES that the increases are hitting school budgets every year, taking money away from other essential expenditures such as staff, books and improving facilities.
Dr Dunford said: "We believe it is absolutely essential that the costs of examinations are brought down. According to our surveys, the costs of exams is the second biggest item in school budgets after staffing, which has to change.
"The Government calls for changes to the examination system on an annual basis, which results in the awarding bodies developing new specifications, the costs of which are passed on to the school and college budgets. The reasons schools put up with it is because they want to do the best for their students."
One of the main awarding bodies, OCR, attributed the rise in costs to growing numbers of students taking exams, students taking more exams, and a hike in fees.
An OCR spokesperson said: "There are a lot of cost drivers when it comes to examinations, not all of which are in the control of the exam boards.
"Many of them are found to be coming out of government and quasi-governmental organisations.
"Also the fees, including the design and creation of syllabuses and thousands of insets, particularly for new qualifications, all add to the overall costs."
The AQA exam board said it tried to keep its fees as low as possible, adding that its activities are not for profit. A spokesperson said: "AQA's fees are set by the finance committee, which includes headteachers and principals who are aware of the financial pressure on schools and colleges.