Pupils will be able to gain the new "work-related" diplomas without any experience of a relevant workplace, The TES can reveal.
Ministers have said that the courses, which start in September, will give 14- to 19-year-old pupils hands-on experience and employer-based learning.
But the compulsory minimum of 10 days' work experience does not have to be in a relevant industry. Pupils will be able to pass a construction diploma without ever visiting a building site; or they can gain the engineering diploma after doing work experience in a totally unrelated business, such as a travel agency or department store.
Part-time work will also count, even if it, too, bears no relation to the qualification's subject. A bemused source, close to the development of the diplomas, said: "In theory, a paper round could count."
Headteachers connected to the diplomas say there is a huge commitment to making them work. However, the revelations raise fresh questions about the qualification's ability to deliver learning that is valued by industry.
Sources working with business said few firms were aware of the qualifications, despite support from leading multinational companies.
Guidance from the Qualifications and Curriculum Authority states only that the work experience should be in a relevant work sector "where possible".
Further guidance, published by the construction and the built environment diploma development partnership in draft form last month, said: "There is not a mandatory requirement for the work experience to be in the (relevant) line of learning."
Joe Johnson, director of training at the Civil Engineering Contractors Association, said: "A holder of the construction and the built environment diploma might not have set foot on a construction site during the entire course. For it to work, you've got to get the vast majority of work experience on-site. Pupils have to get their hands dirty."
Graeme Miller, of the Tyne and Wear Education Business Link Organisation, which liaises with 3,000 employers on providing work experience, said: "The whole point about work-related learning is that you need to do it in the workplace."
The Government has said that the diploma could become the qualification of choice for 14- to 19-year-olds within five years, when it will be offered in 17 subjects. This would create huge demand for work experience placements if they are to be meaningfully related to the subject, particularly in areas without firms in a particular sector.
Peter Hawthorne, a former head who has led preparations for the introduction of the diploma to schools and colleges in Wolverhampton, said: "The whole thrust is about working with employers. Our pupils will have much more than 10 days' work experience with a relevant employer."
A QCA spokesman said: "Work experience within the diploma supports the development of employability skills and is intended to be linked to the young person's curriculum.
"This may be in the line of the learning area, or it may be in another area which supports work-related skills. It is not the purpose of the diploma to make young people job-ready."
Head's advice, page 12.