The chair of the exam regulator has said that IGCSEs that can only be taken by independent schools are undermining public trust in the exam system and a "problem".
Roger Taylor, the Ofqual chair, also suggested that exam boards should rebrand IGCSEs so they do not "use the same terminology and language" as GCSEs.
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'IGCSE' is a term used as shorthand for a family of alternative key stage 4 qualifications that are provided by a number of exam boards.
State schools used to be able to take IGCSEs until a decision was made by the government in 2014 to remove the qualifications from official league tables. However, many private schools continue to take them.
Questions have been raised about the fairness of this system, with some claiming IGCSEs are easier than reformed GCSEs. An analysis by FFT Education Datalab in January suggested that IGCSEs are not graded as severely as reformed GCSEs.
And a Tes investigation in August found that found some universities were offering relatively lower requirements for alphabetically graded IGCSEs than for the numerically graded reformed GCSEs.
Asked about IGCSEs during an Ofqual hearing at the House of Commons Education Select Committee this morning, Mr Taylor said: “It is a situation that is not really conducive to public trust in the examination system, and I think it is a problem.
“It is an issue of concern. Our view would be that these qualifications, they are not systematically easier, however, they are not comparable and they are not regulated in the same way which means that a particular subject in a particular year will be easier, and we don’t have the mechanisms to do anything about that."
Mr Taylor said much of the problem was owing to the way IGCSEs were branded.
"If you’re a private school in this country you can do whatever qualification you want and you can present it to a university," he said. "The International Baccalaureate, for example, is taught in some schools and used for university.
"It doesn’t create the same confusion, because it doesn’t use the same terminology and language. I think the most helpful thing perhaps would be if the exams boards did not label their qualification [as IGCSEs]."
He later said that Ofqual was in discussions with the Department for Education “around the use of the term GCSE”.