Figures released this week by the Department for Education show new sixth forms are being approved at a rate of almost two per month.
Since new guidelines for schools wishing to set up sixth forms were announced last February by former education secretary John Patten, 20 applications have been approved by the DFE.
Fourteen out of the 20 new sixth forms are in grant-maintained schools. In contrast, nine out of 16 applications rejected were in LEA schools. Prior to last February, just 14 new sixth forms had been approved in 22 months.
But the worst news for FE colleges, which fear growing competition from sixth forms, is that a further 42 applications are still awaiting a decision.
"There is a constant stream of applications," said a DFE spokeswoman. The increasing number of proposals being made by schools has forced the Further Education Funding Council to take a more robust line against new sixth forms.
Last month the FEFC made statutory objections to 13 proposals (including six from GM schools). It said it would have objected to a further seven (five GM) if it had been consulted in time. Officials from the FEFC, which is due to publish a circular on the subject next month, have asked the DFE to take a fresh look at the cumulative effect which new sixth forms may have in some areas and consider how this will affect the viability of colleges.
A survey of 251 college principals carried out last summer showed overwhelming opposition to the growth of sixth forms which, it was claimed, would lead to wasteful duplication and reduce students' choice by damaging the minority subjects.
Four principals who carried out the survey and who have been lobbying the DFE over the issue met education minister Tim Boswell in November.
Mike Snell, principal of Brockenhurst College in Hampshire, said Mr Boswell had asked them to produce specific evidence of cases where new sixth forms would harm overall post-16 provision. The meeting had been constructive and Mr Boswell was aware of their concerns, he added.
When told of the increasing number of new sixth-form proposals and the number approved by the DFE since February, Mr Snell said: "It's very alarming. We have still not got to the bottom of the Government's policy either in its formulation or application."
Twenty-three of the 42 applications awaiting a decision were made by GM schools. Cecil Knight, chairman of the GM Schools Advisory Committee, said he understood the concerns of the FE sector.
"We hope there are enough checks and balances within the system to ensure balanced decisions are reached about 16-18 provision," said Mr Knight, who is the headteacher of Small Heath School, Birmingham, which opened a sixth form last term.
A study carried out last year by the National Foundation for Educational Research showed that local authorities which oppose new sixth forms had reluctantly supported applications by LEA schools to try to discourage them from opting out.
Although just a handful of schools in Wales have submitted applications for new sixth forms. The FEFC for Wales has said it is unlikely to support a significant proportion of future proposals. The council has already backed the objections of a North Wales college against a proposed sixth form at Bala in Gwynedd.
Professor John Andrews, chief executive of the FEFC for Wales, said many schools would not be able to provide a sixth form with a significant range of courses. "They would reduce substantially the choice available to post-16 students who attend," he said.