The government is to crack down on bad employers and ensure those who work for free get paid what they deserve.
167 interns and those on free work experience placements had wages paid last year after the Department for Business Innovation and Skills (BIS) intervened in their cases.
In total nearly £200,000 was reclaimed, and BIS is aiming to fight more cases this year.
It will publish a leaflet shortly advising interns on their rights, and will launch a social media campaign to back this up.
Employment Relations Minister Jo Swinson confirmed that complaints to the BIS pay and work rights hotline would be dealt with as quickly as possible.
Those who see adverts for unpaid jobs that breach guidelines, for example by being long-term and including few learning opportunities, are also encouraged to contact the hotline.
Labour MP Hazel Blears, who helped to establish a paid internship scheme in the Houses of Parliament in 2011, called on other MPs to stop employing unpaid interns, saying they were "taking advantage of the drive and commitment of young people... [expecting them] to live and work for free is exploitative, unfair and just plain wrong".
Job site Monster stopped advertising unpaid internships in April, with managing director Andrew Sumner saying:
"A healthy future economy relies on the investment businesses make in young people and we believe it's important not to take advantage of those desperate to get a foot on the career ladder.
"We will happily remove any postings that our users alert us to, if these are found not to comply with the minimum wage law."
Are you being exploited at work? Contact the government's pay and work rights hotline.
UnemployedNet has developed some rules for work experience - read them here.