The region got the lowest rating in a national quality survey by the Training Standards Council.
Top performers include the East Midlands and London, where more than 40 per cent of employers were given high grades of 1 or 2. In Yorkshire and Humberside, more than 30 per cent of the grades were 4 or 5 - the lowest possible.
The TSC, the Government's workplace learning inspectorate for England and Wales, is replaced by the Adult Learning Inspectorate next year. It inspects every government-funded work training scheme longer than four weeks.
The TSC says it is encouraged by the fact that, while regional differences remain, most sub-standard training programmes improve dramatically by the time they are re-inspected.
The figures, published in the report for 1999-2000, show 85 per cent of providers who got "unsatisfactory" grades last year were at least "satisfactory" by the time they were re-inspected.
TSC chief inspector David Sherlock said: "Noboy is better at improving fast than training providers.
"There are brave managers in work-based learning. They face up to weaknesses quickly, take their staff and trainees with them and use the quality-assurance techniques of modern business."
Where there has been improvement, the TSC says, is largely due to to the work of the training and enterprise councils.
Future reports will reveal whether the improvement continues when the training functions of the TECs are taken over by the local Learning and Skills Councils. Other key points revealed in the report include:
Using up-to-date learning resources and equipment improves the quality of training.
Few staff are qualified to train in key skills or assess them - with 15 per cent of providers not assessing key skills at all.
Initial skills assessment is rarely carried out, so employers don't know what skills employees already have before they join a training programme.
Standards of competence are poorly monitored in the work- place - with internal verification only being carried out in 55 per cent of cases.