The exams system is "diseased", "almost corrupt" and allows "insider dealing" from chief examiners, a senior member of the former qualifications regulator has claimed.
Exam boards are competing in the market place by implying to schools that their qualifications are easier than their competitors', according to Mick Waters, who was director of curriculum at the now defunct Qualifications and Curriculum Authority until last year.
He also accuses the new exams regulator, Ofqual, of lacking "the nerve" to ask "awkward questions".
Mr Waters also said Ofqual should "immediately" stop chief examiners from writing textbooks on exams, a practice he said was "insider dealing".
A highly respected figure in education, Mr Waters had chosen not to ruffle many feathers since leaving the QCA, which regulated exams until 2008.
But his outspoken comments, published this week in a book on Labour education policy, reveal that it was his time at the authority that prompted his concerns.
"Before I went for this job (at the QCA), I used to think that all this criticism of exams that they were being dumbed down was unfair," he said. "Since I've been there, I think the system is diseased, almost corrupt."
He added: "We've got a set of awarding bodies who are in a market place. In previous jobs, I had seen people from awarding bodies talk to headteachers implying that their examinations are easier. Not only that, 'We provide the textbook to help you through it'."
John Bangs a visiting professor at London University's Institute of Education and one of the book's authors, said: "The exam boards are in the last-chance saloon. The argument for a single awarding body is becoming overwhelming."
Mr Waters exempted the QCA and Ofqual from his "diseased" and "almost corrupt" claims, but cast doubt on whether Ofqual would regulate effectively and "ask awkward questions".
"I'm not sure that's going to happen," he said. "I don't think they've got the nerve."
Isabel Nisbet, Ofqual chief executive, said: "Ofqual will investigate any allegations of conflicts of interest or 'insider dealing' about regulated qualifications.
"We are fully prepared to ask difficult questions about the examinations we regulate."
A spokesperson for the Cambridge Assessment board said: "Mick Waters' inflammatory and polemical commentary fails to engage with the reality of the system which the interventions of the QCA - of which he was a director - created."
An OCR spokesperson said: "OCR has never claimed that its exams are easier. It competes on quality of service, training and support for teachers, and educational integrity."
Andrew Hall, director general of the AQA board, said: "Clearly assessment is an important issue and its integrity is dealt with by the regulator."
An Edexcel spokeswoman said: "We have never said our exams are easier. All our qualifications are rigorous, fair to learners and represent the highest possible standards."
- Reinventing Schools, Reforming Teaching: From Political Visions to Classroom Reality by John Bangs, John MacBeath and Maurice Galton.
Book excerpt, pages 34-35
Puttnam: 'I diddled Blunkett'
Lord Puttnam, founder of the Teaching Awards, has revealed his creativity in ensuring that the education secretary went ahead with the scheme in 1998.
Interviewed for Reinventing Schools, Reforming Teaching he said: "My deal with David Blunkett was that we wouldn't go ahead if we couldn't get a sufficient nominees.
"I got him down to 800 and on the night we closed we had 796. So I sat down with the chief executive and created eight additional nominations. I went back to David and said: 'That was close, 804.' He said: 'That's good enough.' You'll be pleased to know none of our nominations won."