SYDNEY, Sept. 21 (Xinhua) -- The former operators of a fast-food chain in Australia's Queensland state have been fined more than 72,000 Australian dollars (52,500 U.S. dollars) for underpaying their non-English-speaking staff, authorities said on Friday.

The case involved a 71-year-old employee who was born and raised in China working at a "Wok Me" outlet in Rockhampton city, where he was underpaid nearly 13,000 Australian dollars (9,480 U.S. dollars) over four months in 2016 by former outlet owner and operator Luke McGrath and his company, the Fair Work Ombudsman government workplace relations regulator said in a statement.

"The significant underpayment over such a short period was a result of the worker not being paid any wages for eight of the weeks he worked," it said.

"Overtime, annual leave and superannuation entitlements were also underpaid and record-keeping and pay slip laws were breached. The worker has now been back-paid in full."

"Mature age employees can be vulnerable in the workplace as they face fewer opportunities and are often reluctant to complain. The Fair Work Ombudsman took court action against Wok Me because we prioritize matters involving the underpayment of vulnerable employees," the regulator's head Sandra Parker said.