Low rates of completion by trainees on Modern Apprenticeships has prompted ministers to consider new powers and incentives for employers.
Only a third of Modern Apprentices reach NVQ Level 3, official figures show. The rates vary from 40 per cent for engineering to only 11 per cent for retail.
The findings are reported in this month's issue of Training magazine.
A spokesman for the Department for Education and Employment said it wants to see "carrots and sticks" to reverse the low accreditation rates. This could involve withholding a portion of the grant until completion, although no further details are available at this stage.
But training managers argue that forcing employers to comply is not enough and claim the system must be improved.
Corus, formerly known as British Steel/ Hoogovens, said 100 of its 600 modern apprentices have reached Level 3 since they began in 1995, but that this is not due to people dropping out.
"We are more concerned with resources. Assessment costs money - you have to get someone to do it and it is not their main job," said Joe Eason, training and education manager at Corus.
Delays were caused when the Government introduced separate certification for basic skills in 1998, he added.
George Edwards, development director at the Institute for Supervision and Management, said, "One problem with the scheme was always going to be the Level 3 outcome.
"It includes the presumption that there may be some supervisory responsibility but it is very unlikely that a modern apprentice would have such responsibility."
By Philip Whiteley