The survey, carried out by consultancy firm Host for the Department for Education and Employment, found that the planning, delivery and support of work- based learning gives "cause for concern".
Host looked at 5,100 vocational trainers in eight Training and Enterprise Council areas, identifying "recurrent skills gaps" among the estimated 95,000 to 110,000 deliverers of government-funded work-based training in England.
Inexperienced staff, weak management and resourcing pressures led to poor planning. Design skills were "unimaginative", learner support "inconsistent", competence "limited" and communications skills "poor".
"Too often those involved in planning, managing and delivering government-funded work-based learning lack the skills or knowledge to undertake the roles they are asked to perform. Many also lack qualifications directly relevant to their roles."
The study saysthat while some providers do a good job, evidence from the Training Standards Council - the watchdog due to be replaced by the Adult Learning Inspectorate from next April - points to significant shortfalls in staff training and skills.
Low take-up of training was blamed on the cost of courses, reluctance to give staff time off for training and an emphasis on staff with narrowly defined qualifications.
Providers themselves expressed concern about the usefulness of some commonly available assessment and verification qualifications, particularly the D3233 assessor awards.
"Many current practitioners may not hold formal qualifications but have high levels of competence from experience. Others with qualifications may be less competent than non-qualified but experienced staff, through inexperience or weak assessment."
It identifies eight "key functions" for skills-based standards, most of which are covered by 22 current employment national training organisation standards.