Soaring numbers of pupils are being entered for a qualification that is often seen as a tougher alternative to GCSEs, new figures suggest.
Schools have made more than 115,000 entries for international GCSE exams - known as IGCSEs - this year, double the number made a year ago, according to Cambridge International Examinations' (CIE) latest data.
The exams have long been favoured by many private schools, who argue that they are tougher than traditional GCSEs.
But the figures suggest that IGCSEs are also becoming increasingly popular with state schools after a decision by ministers in June 2010 to allow these schools to offer the qualifications.
CIE's latest data shows that the number of UK state schools taking IGCSEs has nearly tripled, with 963 now offering the qualification compared with 368 in June last year.
It also reveals that IGCSEs in traditional academic subjects are increasingly favoured by schools.
The number of entries for IGCSEs in English (literature and language), chemistry, physics and biology has almost tripled in 12 months, CIE said, rising from 34,800 for June 2012 to 93,300 for June this year.
IGCSEs are usually "linear" meaning they have exams at the end of the two-year course, while in recent years many GCSEs have been modular, with students sitting papers in chunks throughout.
Ministers and the exams regulator Ofqual are now making changes to bring final exams back to GCSEs. The move is part of a bid by the Government to toughen up the qualifications.
CIE chief executive Michael O'Sullivan said: "Cambridge IGCSE has grown significantly in popularity over the past few years. Schools recognise that its linear structure offers rigour and effective preparation for the next stage of their students' education.
"For sure, they are also mindful of planned educational reforms such as the recently proposed changes to GCSEs and A-levels."
A breakdown of the CIE's figures show that they have had 84,659 entries for IGCSE English this year, compared to just over 31,000 last year.
And the number of entries for the three sciences combined rose from 3,797 last year to 8,689 this year.
Separate figures from Pearson, which also offers IGCSE qualifications to schools, show a rise in entries.
The board said that there had been 99,605 entries for the 2012/13 year - up 28% from 77,697 entries in 2011/12.
High numbers of these were also in academic subjects - including more than 11,000 entries each for biology, chemistry and physics, and around 25,387 entries combined for two maths IGCSEs.
A Pearson spokeswoman said: "The continuing popularity of IGCSEs in this country and abroad supports our view that students should be able to choose the qualifications that suit their style of learning and interests."