Urgent action is needed to correct flaws in the Government’s forthcoming schools’ diploma course, the head of a leading exam board has said.

The new system for 14 to 19-year-old pupils “risks failure” when it is introduced this September because of a lack of properly trained teachers and other problems, claimed Jerry Jarvis, the head of Edexcel. The Government believes that the diploma system, combining practical skills with theory, could replace A levels and GCSEs as the dominant schools qualifications.But Mr Jarvis said that teachers had not been trained adequately, schools did not know how new features should be taught, and there were fears that the qualification would be too demanding for pupils.

In some cases, this meant that pupils could come away with no qualification at all, he added. Mr Jarvis said that he fully supported the diploma, but it was crucial that the Government and exam authorities acted to ensure its success.

“We think it’s going to be quite traumatic to get through this. The issue is about schools being able to cope.

“If the diploma doesn’t earn its spurs as a qualification, and that means respect from employers, pupils, parents and higher education, we face a serious problem,” he told The Guardian. “There is a huge educational risk to this country.”

Teachers would have had only three days’ training before the diploma’s launch in September, according to Mr Jarvis.

He added that no decision had been made about how to teach the “functional skills” element of the diploma — a version of English and maths that is geared towards practical skills such as calculating a mortgage.

Because the diploma was broader than traditional qualifications, and students were required to pass all elements, more of them might end up with no overall qualification at all because they might fail one component in which they had a particular weakness.

A spokesman for the Department for Children, Schools and Families said: “This is an absurd misrepresentation of the truth. As Edexcel has made clear, it is fully behind the diploma.”

Jim Knight, the Schools Minister, said: “The diploma is going from strength to strength and has received widespread support from schools, colleges, universities and employers.”

Last year Alan Johnson, when Education Secretary, admitted to education leaders that the diploma plan could go horribly wrong .

Despite describing the plan as the most radical education reform anywhere in 40 years, he said that the diplomas could be considered inferior to GCSEs and A levels.

Last month teaching leaders said that the new diplomas would fail as long as they were forced to compete with traditional A levels and GCSEs, which would continue to be favoured by middle-class parents.

The Association of School and College Leaders also gave a warning that teenagers and their parents would be reluctant to make the leap of faith required to sign up to the new, untested, qualifications.

The Government is hoping that the diplomas will be respected by universities and business leaders alike, and will encourage more teenagers to stay on at school after the age of 16.

Times recommends

• Screen tests are the future of exams
• No more free boarding schools for diplomats
• Popular Jewish School broke race laws