Young people undertaking modern apprenticeships are being "exploited", with more than one in 10 receiving less than the appropriate minimum wage, NUS Scotland has warned.
This "shocking" situation has developed despite the Scottish government heavily promoting apprenticeships and other vocational courses to school pupils as well as older learners.
Ministers this week announced that the government was on course to exceed its annual target of 25,000 modern apprenticeship new starts, with 78 per cent of places filled at the end of the third quarter of 2014-15. Half the new apprentices were aged 16-19, slightly up on the previous year. The government plans to increase its target to 30,000 new starts each year by 2020 as part of its strategy to tackle youth unemployment.
But NUS Scotland education vice-president Robert Foster said the push to increase apprenticeships must be accompanied by a pledge to guarantee better pay.
"It is shocking to see that some young people are still not paid the apprentice minimum wage," Mr Foster said. "Even one apprentice paid below the minimum wage is one too many and we need to see this exploitation of young people put to an end."
Research by the Department for Business, Innovation and Skills, published last year, shows that 13 per cent of all level 2 and level 3 apprentices in Scotland were paid below the national minimum wage for their age in 2014 (bit.lyApprenticeWage).
The pay rate should be pound;2.73 per hour for those aged 16-18 and older apprentices in their first year, and pound;5.13 per hour for those aged 18-20.
The Scottish government is in the process of implementing the recommendations made by the Commission for Developing Scotland's Young Workforce. These aim to improve the links between schools, colleges and employers, and increase vocational opportunities for pupils.
Foundation apprenticeships are already being piloted by schools in some council areas, in the hope that they will enable young people to go on to modern apprenticeships, jobs, or further or higher education.
According to the BIS figures, pay for modern apprentices varies considerably between sectors: 44 per cent of hairdressing and almost a quarter of health and social care trainees receive less than the minimum wage, but only 3 per cent of level 2 and 3 apprentices in retail and customer service.
NUS Scotland has also raised concerns about variations in pay between male and female apprentices. Unlike in the rest of the UK, where there is no difference in pay between the genders, male apprentices in Scotland are paid a higher wage on average than their female counterparts.
Female-dominated areas such as childcare and hairdressing receive the lowest average hourly pay, at pound;4.23 and pound;4.29 respectively, whereas apprentices in male-dominated electro-technical industries are among the highest paid at pound;10.10.
Hugh Aitken, director of CBI Scotland, said that employers could not be solely responsible for bearing the wage burden of apprentices. "An important way to ensure that we can deliver enough high-quality opportunities is to ensure that the cost of delivering them is shared between those who reap the rewards," he said.
"This means the cost of the significant investment the employer makes in training and support is shared between the employer, government and the apprentice, through a lower wage."
Roseanna Cunningham, cabinet secretary for fair work, skills and training, blamed the low pay of apprentices on the Westminster government.
"The Scottish programme ensures employed status, and yet the discriminatory regulations of the UK government mean that many could receive less than pound;3 an hour," she said. "That is simply wrong. That's why I am today calling upon Westminster to bring payment for apprentices into line with the other bands in the national minimum wage."