The Department of Labour is looking into a complaint that migrant workers in Auckland are being exploited.
An Indian businessman, Ram Rai, laid the complaint saying migrant workers are scared of speaking against their employers and have asked him for help.
He says most migrant workers who are on work permits or student visas are being made to work for 40 hours, but are being paid for 20.
In one case, he says a student from India was employed by a restaurant owner for four weeks without pay because the employer said the student was under training.
In another case, three employees on work permits were not paid what was offered in the contract submitted to Immigration.
Mr Rai says they were made to work 60 hours per week and were underpaid.
The department says it is aware of the issue and is taking action.