The parent company of 7-Eleven says it will take action against franchisees flouting the law in Australia.
"7-Eleven is extremely disappointed that a number of franchisees have chosen not to meet their obligations as employers," a statement released on Saturday said.
A joint Fairfax-Four Corners investigation found up to two-thirds of 7-Eleven stores could be underpaying workers.
It also said some franchisees were threatening to report international students to the immigration department unless they worked double shifts for less money.
"We are deeply concerned about the personal impact on affected employees or former employees, and the damage such actions cause to franchisees who are trusted, reliable and responsible small business owners," the parent company said.
"We do not and will not hesitate to take any appropriate action, under law and within the franchise agreement, where a franchisee is found to be in contravention of the law."
Greens MP Adam Bandt said Australia's labour law enforcement needed to be improved.
"Something is wrong in Australia when the boss of 7-Eleven is a billionaire but its workers are getting paid under $10 an hour and threatened with deportation," he told reporters.
"Far too much of the enforcement of our labour laws is left up to the businesses themselves."
Mr Bandt urged a Senate inquiry into working visas to hold a special hearing into the claims against 7-Eleven.
The company franchises about 620 stores around Australia to 450 franchisees.