The owner of a successful business who established a school to train young apprentices has called on the government to close "legal loopholes" which would end the decline in apprenticeships.

Kevin McLoughlin, who owns K&M McLoughlin Decorating Ltd, made the comments after his school in Islington, north London, was visited by the deputy prime minister on Monday as part of a move to promote the Youth Contract - a £1bn project to help young people get employment.

Nick Clegg toured the premises and met students at the school where young people learn their trade.

The firm was started in 1988 by Kevin McLoughlin, who worked his way up from being an apprentice to owning the company, which has a turnover of more than £6m a year.

It has been involved in some of the capital's biggest building projects, such as the Olympics sites, St Pancras station and the Savoy Hotel's redevelopment.

The firm opened its decorating school in October 2010 and now has 22 apprentices.

McLoughlin, 54, said the last 25 years has seen 90% of companies stop training youngsters.

"It is mainly due to the major contractors," he said.

"They have systematically driven down prices, causing a downward spiral where, to claw back profit, many sub-contractors have been forced to cut costs to the bone.

"Training has been seen as 'expensive' and apprenticeships have been the casualty.

"But the sums are wrong. Believe me, I'm not a charity.

"I wouldn't do this if apprentices did not make me money and, in return, they get the opportunity to learn a trade with a guarantee of a job at the end of it."

He added: "If the government was truly committed to apprentices, they would close the legal loopholes that allow companies to sub-contract their workforce on a long-term basis, whether that is through an agency or the traditional labour-only sub-contract route.

"This allows them to avoid PAYE and all the associated employment costs.

"Without PAYE staff, you cannot take on apprentices because there is no infrastructure there to mentor and train them."