The Fair Work Ombudsman has launched legal action against a national advertising company, alleging it underpaid 45 workers almost $60,000.


OHMedia Melbourne and company director and part-owner Wen Zhou, also known as Joseph Chou, will face the Federal Magistrates Court this month.


It is alleged the company underpaid 45 casual workers in Brisbane, Sydney, Melbourne and Adelaide a total of $59,145 between March and April 2011.


The staff worked at stalls outside supermarkets promoting prepaid SIM cards and top-up vouchers supplied by global telco Lycamobile, a major client of OHMedia Melbourne.


Several of the staff were foreign nationals who were in Australia on student and working holiday visas.


It is alleged more than $48,000 of the underpayment relates to 34 Brisbane-based employees - including seven juniors aged between 18 and 21 - who worked up to 133 hours without pay.


Complaints by staff to the Fair Work Ombudsman prompted the investigation.


Fair Work Ombudsman Nicholas Wilson said the amount of the alleged underpayment and the vulnerability of the staff were factors in the decision to prosecute.


''Foreign workers may not necessarily be aware of their full entitlements in the workplace and are therefore particularly vulnerable,'' Mr Nicholson said.


The company could face penalties of up to $33,000 for each proved breach.


The Fair Work Ombudsman is seeking a court order for back-payments to the workers.


AAP