External assessment is set to be introduced for the first time to BTECs - schools' most favoured GCSE alternative - in a bid to ensure they continue to count in league tables.
Exam board Edexcel is considering making at least a fifth of the marks for its hugely popular qualifications dependent on either exams or other types of external assessment from next year.
BTECs, which account for 13.5 per cent of all schools' league table "GCSE" scores, are currently completely teacher assessed, with external moderation.
The news follows last month's Wolf review of vocational education, which said schools' use of BTECs and other "vocationally related" qualifications had "exploded" since 2003 because they were judged GCSE equivalents for league tables.
Ministers are now following the report's recommendation and deciding which of the many existing "equivalent" qualifications should count towards the "anchor" measure of five A*-C GCSEs including English and maths in future.
Edexcel says it is planning its BTEC changes in "the context of the Wolf review" and hopes they will strengthen the case for the qualification's inclusion.
Rod Bristow, president of Pearson UK, Edexcel's parent company, said: "We're very confident that BTEC is a highly valuable qualification, but we are always looking at new ways to raise the bar, to continue to stretch as well as engage students.
"We're considering a range of measures, including more support for schools and introducing some form of external assessment.
"There are many models for external assessment, with exams being just one, and we are engaging with teachers in schools and colleges to consult with the people that know best what will support them and their students."
The board could decide to vary the type and amount of external assessment in BTECs according to the subject. But it says it is unlikely that any will end up completely externally assessed.
External assessment could take the form of performances in subjects such as music or controlled assessment, as well as exams.
The Wolf review showed that 14 of the 30 most popular vocational qualifications in schools were BTEC first diplomas - worth four A*-C GCSEs in league tables - or BTEC first certificates - worth two.
It raised concerns that league table equivalences for vocational qualifications in general did "not necessarily translate into real equivalance". The report raised science as a "special concern", noting that BTEC science - the most popular of the BTECs - did "not allow progress to science A-levels".
Edexcel had made this fact "absolutely clear", the report noted, but many pupils were unaware of the lack of A-level progression.
VOCATIONAL QUALIFICATIONS: `A JOURNEY TO IMPROVEMENT'
Vocational qualifications are used by schools as part of a "journey to improvement", Michael Gove has said. The education secretary had previously described the use of some "equivalents" as "morally wrong".
He made his latest comments when asked why some academy chains he had highlighted for "driving up standards" were failing on the English Baccalaureate, his favoured GCSE measure of academic rigour.
Mr Gove said: "If you look at schools that have been underperforming or have had in comparative terms relatively poor GCSE results over time as they go on a journey to improvement, they tend to use equivalences and that is true of academies and non-academy schools."
As they became stronger "their reliance on equivalences" diminished, he added.
"Academy principals recognise that it is often important to stabilise by getting English and maths right and then move on."
Original headline: Edexcel moves to keep BTECs in league tables