The central components of the Government's flagship Diplomas are too easy, the qualifications regulator said today.
In its first official scrutiny of the core elements of controversial new courses, Ofqual looked at the principal learning qualifications in three of the 14 Diplomas and found all were lacking in the demand they posed to pupils.
In a separate report, also released today, the exams watchdog uncovered similar problems in AS-levels in geography and physics.
Ofqual found principal learning written exam questions for Diplomas in engineering and society, health and development were not challenging enough, which could affect the awarding of A* grades.
Furthermore, internally assessed work for the society, health and development Diploma run by the Edexcel board was not of an "appropriate" standard.
And for the externally assessed part of the creative and media Diploma, it found the quality of work completed by candidates was of a "lower standard" than supposedly equivalent qualifications.
The Government defended the Diploma, insisting that overall Ofqual's findings were "very positive". But the report is the biggest yet in a long line of blows to the qualification's credibility.
It follows last week's warning from Sir Mike Tomlinson, who inspired the qualification, that the "academic" versions would lack content and needed structural change.
Heads of exam boards have warned that the Diplomas are being introduced too quickly.
This week a spokesperson for the OCR board, which set the principal learning tests in the creative and media Diploma, said: "These are early days for a new qualification, so there are inevitably things we can improve on. However, we are surprised that Ofqual is now criticising aspects of marking which were set out in the specification it accredited."
The regulator had said the board's marking criteria was "confusing", with little guidance for examiners on how it should be applied.
On the engineering diploma run by the AQA and City and Guilds board, and the society, health and development course from Edexcel, Ofqual said of the principal learning elements: "There were limited opportunities for candidates of higher ability to show the extent of their knowledge, understanding and skills through extended writing or interpretation of data."
An AQA spokesperson said: "We look forward to working closely with Ofqual to continue improving the delivery of our principal learning qualifications and providing first class support for teachers and learners."
Edexcel said it had agreed an action plan with Ofqual to "address the minor concerns identified".
A Department for Children, Schools and Families spokesman said Ofqual's report "underlines that the Diploma is a high-quality, rigorous and challenging qualification".
The regulator's report on AS-levels said written papers from AQA in geography and Edexcel in physics "did not provide enough opportunities for more able candidates to demonstrate what they knew, understood and could do".
As a result, the sample of candidates' work looked at was "below expectations" at the AB grade boundary.
The DCSF spokesman said it welcomed the action Ofqual was requiring exam boards to take to remedy the problems.