Government funding cuts will soon mean only independent schools can afford to offer the International Baccalaureate (IB), state school heads have warned.
Several state schools are understood to be dropping the IB or abandoning plans to switch to it, The TES has learnt. Shrinking sixth-form budgets are expected to force more to do the same in the next three years.
The news comes despite repeated calls from ministers for state schools to adopt the qualification.
Education secretary Michael Gove said in September he was "determined to support a wider take-up" of the IB, an alternative to A-levels that comprises six subjects, community work and an extended essay.
Last February Mr Gove praised the IB, saying he wanted to give "students in poorer areas the chance to do the sorts of prestige exams that currently only rich kids can do".
But his Government's financial decisions are having the opposite effect, according to Sandra Morton, chair of the IB Schools and Colleges Association, which represents the 143 state schools already offering the qualification.
She said that if budgetary problems were not resolved, "able and committed students in the state sector would be denied equality of access to this highly regarded programme".
Paul Luxmoore, executive head of Dane Court Grammar in Broadstairs, Kent, said: "The Government is about to throttle the IB without realising it."
He has offered the qualification for three years but is "desperately concerned" he might have to ditch a wholesale move to the IB next year because funding cuts will make it impossible.
"In three years no state schools will be doing the IB and the only way to access it will be if your parents have got enough money to send you to an independent school," Mr Luxmoore said.
The heads say funding cuts for school sixth-forms from September are exacerbating existing inequities in IB funding.
Money for the qualification is capped at the equivalent of four-and-a-half A-levels, but the schools that offer it say it is regarded as the equivalent of five and a half for Government league tables and six A-levels by UCAS.
The schools also note that the funding formula used by the Young People's Learning Agency (YPLA) recognises the additional cost of delivering subjects like science for A-levels but ignores it for the IB.
The YPLA and the Government say they are not cutting "core academic funding" and are paying for more teaching hours than recommended for the IB.
But the heads say a reduction in "enrichment funding" - money they have been able to use towards the supervision of IB community activities - and the lack of flexibility in such a big qualification will make it increasingly difficult to offer as sixth-form cuts bite over the next three years.
Adrian Kearney, the IB's Europe director, said the reduction in funding for UK schools was "reaching a critical stage".
David Smart, executive head of the Chatham and Clarendon Grammar School Federation in Ramsgate, had planned to switch his 530-pupil sixth-form from A-levels to the IB next year. But in a "bitter disappointment" he has now dropped the idea.
He is expecting sixth-form funding to drop from just under #163;5,000 per pupil to just over #163;3,000 by 2013, making the move "unaffordable".
A YPLA spokesperson said: "Our priority with the 201112 funding allocation has been to protect the main programme of 16-19 learning and education.
"Young people can be funded for a programme of 4.5 A-levels or their equivalent. This position has not changed from previous years."
A Department for Education spokesperson said: "We have not reduced the funding for core academic programmes in 201112. The International Baccalaureate, along with all other courses, is being funded at the same rate.
"The 16-19 funding formula is currently being reviewed and we will ensure that we take into account issues relating to the delivery of the IB as part of that review."
GOVE ON THE IB
"I am a great admirer of the existing International Baccalaureate and am determined to support a wider take-up of that qualification." September 2010
"What I want to do is to give schools the freedom in the state sector that schools in the private sector have at the moment. Fee-paying schools have all sorts of exams like the International GCSE or the Pre-U or the International Baccalaureate, which are either banned or restricted in state schools." February 2010
"It is a pity that the commitment of the previous prime minister, Tony Blair, to have a school offering the International Baccalaureate in every neighbourhood was one that (his successor Gordon Brown) decided to abandon." July 2010.