Secondary teachers have accused Scottish local authorities of using a controversial reform of the curriculum as a smokescreen for a "demolition job" on the way traditional subjects are run.

The warning follows moves by some councils to reduce the number of promoted teachers in schools by merging different subject areas into so-called faculties led by just one member of staff.

The system was introduced in Scotland by some local authorities after the 2001 McCrone agreement on teachers' pay and conditions, which recognised that having a head of department for every subject was not always cost-effective or necessary.

Some local authorities have merged subject areas such as history, geography and English into faculties under a senior teacher, and there is growing concern that the policy has been pursued too vigorously to cut costs.

Some departments are now also merging unrelated subjects, so faculty heads may have no understanding of subjects they are in charge of. In one case a chemistry department was headed up by a history teacher.

Now, the Scottish Secondary Teachers Association (SSTA) believes the practice is being given greater impetus by the Scottish Executive's ongoing Curriculum for Excellence review.

Matthew MacIver, chief executive of the General Teaching Council for Scotland, has already warned that plans to break down barriers between subjects in the early years of secondary could impact adversely on the "underlying rationale and logical framework" of education.

Last night, David Eaglesham, general secretary of the SSTA, said: "Local authorities are not looking at this from the point of view of what's best for pupils, but are simply driving down costs by ripping out promoted posts for subject specialists.

"The curriculum for excellence is seen as the ideal cover for stripping out these posts and once they are gone it will be easier to drop elements of the curriculum which are no longer wanted. The impact of this demolition job is that once you have removed that layer of expertise, traditional subjects will suffer."

However, a spokesman for Cosla, which represents local authorities, denied the claims. He said: "It is wrong to suggest any local authority is wilfully setting out to deliberately damage the traditional subject-based structures in our schools because of the Curriculum for Excellence.

"In some cases, local authorities have taken the decision that it makes sense to run several similar departments of differing sizes under one faculty. That does not mean that the subjects involved are seen as any less critical."