National Vocational Qualifications (NVQs) and 'vocational A- levels', for which 70,000 pupils are already studying, are failing many students, Professor Alan Smithers, of Manchester University, says.
The courses have no syllabuses and little formal teaching, and on some modules the failure rate is 100 per cent, researchers found.
The report, compiled for a Dispatches programme to be shown on Channel 4 tonight, says the council that oversees the courses has shown a 'disdain' for knowledge.
The National Council for Vocational Qualifications (NCVQ) was set up in 1986 in response to complaints that Britain's training system was inadequate compared with those of its European competitors.
Three pathways were opened. The traditional academic route remains, alongside NVQs, which aim to train people in specific trades such as hairdressing or plumbing. The third route - vocational A-levels, or GNVQs - has broader-based courses that can lead into either higher education or work and focus on areas such as art and design or manufacturing. The Government wants three out of four people to take vocational courses by 1997.
Professor Smithers, director of the Centre for Education and Employment Research, found that while British students spent between 15 and 20 hours per week studying for GNVQs, their contemporaries in France and Germany spent 33 hours on similar courses.
Teachers had little or no guidance on what they should teach, but were simply handed lists of what their students should be able to do by the end of the course, he said. Conventional teaching was discouraged, and students were asked to compile dossiers of evidence that they could perform certain tasks.
There were no formal tests for NVQs. GNVQ students had to pass a test but their result did not contribute to the final mark. Literacy and numeracy were neither taught nor tested as separate subjects.
Professor Smithers said that while the aim of the new system was good, it needed more work.
'Something very odd is happening and people in authority don't seem to be aware of it. All the people we contacted expressed similar concerns, but they all thought they were the odd ones out,' he said.
Tim Boswell, the minister for higher education, told Dispatches: 'There will be some problems, of course, at the beginning. We are always prepared to look at this and to listen to practitioners.'
John Hillier, chief executive of the NCVQ, said that the council disputed much of the information in the report. 'We are very happy to receive constructive criticism of the system and to improve it. I am surprised that the report appears to be factually inaccurate in a number of respects,' he said.