The details of 100 companies accused of breaking the law by using unpaid interns in paid roles have been handed to HM Revenue and Customs by Employment Minister Jo Swinson.
Ms Swinson told Intern Aware that its claims that the unnamed employers broke the law by using unpaid interns could be used as intelligence by officials at HMRC.
In a letter to the campaign group, she said: "I would like to take this opportunity to thank Intern Aware for their help and continued support on this issue.
"The list of employers that you provided will be treated as intelligence by HMRC. Intelligence forms part of the risk process by helping to identify sectors where there is a higher likelihood of non-compliance."
Employers break the law if they fill full-time positions, that would be subject to national minimum wage rules, with unpaid interns.
Intern Aware has campaigned for HMRC to investigate companies which break the law.
Co-director Ben Lyons said he was pleased Ms Swinson had decided to pass the list of employers on to HMRC. He said: "This is only the start and a lot more needs to be done."
A spokesman for HMRC said it did not comment on individual investigations.
A spokesman for the Department of Business said: "The law on the National Minimum Wage is clear. If somebody on a work experience placement or internship is a worker under NMW legislation, then they are entitled to the minimum wage.
"Internships can be a valuable way of helping young people get into work and realise their ambitions. Anyone who feels they are being exploited should contact the Pay and Work Rights Helpline. Their call will be fast-tracked to HMRC who actively investigate any claims of NMW abuse."