Women apprentices earn up to a fifth less than their male peers, according to a new report.
It suggests that apprenticeships are more likely to go to men due to discrimination in the labour market, and the types of jobs for which training schemes are available.
Unesco's 10th Education for All Global Monitoring Report suggests that when it comes to apprenticeships, a gender pay gap still exists in the UK.
It cites research which shows that female apprentices in the UK earn 21% less, on average, while doing their training. And the wage benefit for a woman who has completed an apprenticeship is just 4%, compared with 20% for a man who has done the same training.
It says research shows that in general worldwide "apprentices are often more likely to be men because of discrimination in the labour market and the types of occupations for which apprenticeships are available".
"Young women who have taken apprenticeships get paid less in them, find it harder to get a job and receive lower pay once they are in work," it adds.
The current hourly minimum wage for a UK apprentice who is under 19 or in the first year of their training is £2.65.
The study also reveals that in the UK, schools play a less active role in helping youngsters to secure an apprenticeship. Around two fifths (42%) of secondary school leavers who start apprenticeships apply directly to an employer, it says, while just 10% find them through their connections and 10% secure one through a careers adviser or teacher.
Unesco director-general Irina Bokova said: "As a reaction to the economic downturn and growing youth unemployment, some governments are creating jobs, but neglecting to ensure that all young people learn the most basic skills they need to enter the world of work with confidence.
"Many, and young women in particular, need to be offered alternative pathways for an education. Unsurprisingly, we are now witnessing a young generation frustrated by the chronic mismatch between skills and work. These young people should not be seen as a threat. It is to everyone's benefit that we quickly start realising that they represent an opportunity."