The Education Secretary Michael Gove is urging all state schools to consider ditching GCSEs for the more traditional IGCSEs in advance of the introduction of his new English Baccalaureate in three years' time.
Mr Gove said he would encourage all schools to look at whether the rival exam would be an "appropriate preparation" for his new qualification.
The past few years have seen a massive growth in the IGCSE – which is designed on traditional O-level lines with the emphasis on end-of-course examinations, as will be the case with the EBacc which will be introduced from 2015.
Take-up by UK schools in the past two years has more than doubled, with 900 (400 state and 500 independent) now choosing it compared with just 399 (97 state and 302) in 2010.
But Christine Blower, general secretary of the National Union of Teachers, said: "Schools want stability and confidence in the examination system so will not want to swap and change courses on such a short-term basis."
Opposition to Mr Gove's EBaccs grew yesterday, with the British Dyslexia Association warning they would have an adverse impact on dyslexic students.
* More than 2,000 Welsh candidates have been awarded improved GCSE grades in English as a result of a review of their exams.
In all, 1,202 students with D grades now have a C and 598 with C grades have been given a B. The Welsh Assembly ordered the WJEC to regrade the papers of Welsh students. The Welsh Education minister described the decision as "the swift resolution of an injustice".