Boosting interest among young people in on-the-job training through modern apprenticeships is proving to be a "challenge", the Government has acknowledged.

Cabinet rivals Chancellor Gordon Brown and Education Secretary Charles Clarke clashed last month over university tuition fees but joined forces to drum up interest in modern apprenticeships and said England's economic prosperity depended on tackling skills shortages.

But official figures showed they were still well short of the Government's target of getting 28 per cent of under-22-year-olds started on a modern apprenticeship course by 2004.

The pair launched a task force of industrialists, company executives and trainers responsible for drumming up employer interest in apprenticeships.

Mr Brown said eight million people in Britain, including one-in-five 18 to 24-year-olds, had inadequate skills.

He said: "To push a teenager into the world of work today without any qualification is to put them at lifetime risk of poverty, failure and wasted potential."

Modern apprenticeships can take up to four years to complete and are intended to appeal to 16 to 24-year-olds who are turned off by traditional academic study and want to earn while learning a skilled trade.

Apprentices have to gain a national vocational qualification (NVQ), a technical certificate in their chosen field and pass "key skills" tests in information and communications technology and application of numbers.

Many do day-release sessions at further education colleges but the Association of Colleges said less than three out of ten candidates completed all the elements, while key skills were a major barrier.

For example, young people learning carpentry had to show they could do statistics to A-level maths standards, said a spokeswoman.

Mr Clarke said it would be wrong to make the courses easier but it would be up to the task force to suggest improvements.

Bryan Sanderson, chairman of the Learning and Skills Council, the Government's post-16 education and training funding agency, said about 150,000 under-22s were expected to sign up to the scheme this year - 25,000 short of the target.

The widely reported shortage of plumbers meant 11,000 people had enrolled on the course.

He said: "I think I can promise the shortage will be an item of history in a very short time."