The introduction of advanced skills teachers earning up to pound;40,000, and staff going through the performance threshold immediately receiving increases of the order of pound;2,000, will put immense pressure on colleges, unable to compete with schools.

The National Joint Council for Staff in Sixth Form Colleges has written to lifelong learning minister Malcolm Wicks.

The council, which represents employers and unions jointly, say that their current funding levels are at 80 per cent of those of school sixth forms. In the past they had appointed more staff from schools than they had lost to schools, but in the last two years this trend had been reversed.

Colleges had received more money for growth or widening participation, but some A-level classes already had up to 30 students and further growth was not possible.

The council is seeking an urgent meeting with the minister.