Exam boards are closing down the choice of A-level books because of the proliferation of "approved" texts and cosy commercial tie-ins, according to worried publishing houses.
Critics claim these deals could lead to reduced text choice for teachers and pupils.
The Educational Publishers Council has convened a meeting next month with A-level boards because its members fear a drastic reduction in the number of texts available to teachers as the official "books of the course" dominate the market.
Some publishers believe that contracts are being awarded more on financial grounds than on merit. The system of putting approved texts out to tender is breaking down, they say.
The position has been exacerbated by the Government's decision to reduce the number of A-level courses, thereby reducing publishers' opportunities and putting them under stiffer financial pressure. All A-levels are being re-written to fit the recommendations of Sir Ron Dearing's review of 16-19 qualifications.
Brenda Stones, publishing director of the Oxford University Press educational division, said: "There will be fewer syllabuses and teachers will just buy the book of the course. Before, they would have chosen different books to suit different approaches."
Exam boards are increasingly looking to offer more support and guidance to schools, and linked books are seen as a way of doing this. But Ms Stones believes that some exam boards are looking to exploit their commercial advantage.
"They're asking the publishers to pay them a royalty for the privilege of publishing an approved text," she said.
John Davies, director of the Educational Publishers Association, said: "The concern is that, if there is a small number of boards and they all just choose one publisher each, we could end up with a very limited publishing range.
"If one publisher has the linked book of the course, it's doubtful anyone would want to produce any further material."
But George Turnbull from the Southern Examining Group says that the A-level boards are required to offer as much support to schools as possible. He also defends their response to what he says is an increasingly commercial climate.
"Money's getting tighter, for the exam boards as well as the publishers, " he said. "If you're working with a publisher, there's a commercial advantage to be obtained - it's not unreasonable. Nor does it stop other publishers competing by producing better material."
Another exam board insider said: "A specific course text is very much desired by teachers. The financial constraints on schools are such that if they can just buy a single book, they will."
A spokeswoman for the National Union of Teachers said that any reduction in teachers' academic choice should be strongly resisted.