A packaging business contracted by confectionery giants Cadbury and Mars is the latest employer to face serious claims of wage exploitation after allegedly underpaying workers by thousands of dollars.
Melbourne company Rapid Pak will face legal action over allegations it has been illegally paying workers flat hourly rates of as little as $14 an hour and denying them penalty rates for weekend, public holiday and overtime work. 
Their wages fluctuated according to the number of items they packed each shift.
Investigations by the Fair Work Ombudsman uncovered alleged underpayments of almost $24,000 for three migrant employees, two of whom were in Australia on 417 working holiday visas, at the company's Clayton South warehouse.
The employees, who spoke limited English, lodged requests for assistance and their underpayments have since been rectified.
But Fair Work Ombudsman Natalie James said legal action was under way because this was the second time the agency had received complaints from migrant workers about ACC Services, trading as Rapid Pak.
The previous matter resulted in the company back-paying employees more than $60,000, Ms James said, and the company had been "put on notice" about its obligations to comply with workplace law.
Now, it faces maximum penalties of $51,000 for each contravention, and the director faces $10,000 for each contravention, in the case before the Federal Circuit Court.
The ombudsman is also taking a rare step of seeking an injunction restraining the company from underpaying employees in the future, meaning it could face contempt-of-court charges if underpayments occur again.
Company director and part-owner Ingrid Hsi declined to comment when contacted by Fairfax Media.
The legal action is the latest case to draw attention to the problem of unscrupulous employer behaviour and the exploitation of migrant labour. A string of similar underpayments were exposed this year in farming, manufacturing and hospitality jobs, and at convenience store chain 7-Eleven.
Employment Minister Michaelia Cash last month set up a ministerial working group to weigh new measures to stamp out exploitation, particularly of foreign workers.
Ms Cash hoped it would build on the work of Taskforce Cadena, which was launched this year to investigate illegal practices in temporary visa programs.
"The government has been resolute in our efforts to catch those seeking to take advantage of foreign workers, while also ensuring these workers are better educated about their rights while in Australia. However, more must be done," Ms Cash said.
In Victoria, the Andrews government is preparing to launch a wide-ranging inquiry into labour hire, insecure work, sham contracting and the abuse of overseas workers.
Industrial Relations Minister Natalie Hutchins said public hearings across Victoria, starting this month, would examine the responsibilities of labour-hire providers and companies higher up in the supply chain.