Employment law firm Maurice Blackburn has urged 7-Eleven's head office to step in and guarantee repayments to exploited workers in case its franchises declare bankruptcy to avoid liability for back payments and fines.

The warning comes after the operator of a 7-Eleven store involved in rampant exploitation of its workers was handed a record court penalty of more than $400,000.

The penalty, issued this week, follows revelations in Fairfax Media about systematic underpayment of workers in 7-Eleven stores around the country.

The Fair Work Ombudsman said the court-imposed penalty was the largest it had won after its investigation found 12 employees in Brisbane had been short-changed more than $82,000 which the court said had to be repaid.

However, Giri Sivaraman, who is head of the firm's Queensland employment law department based in Brisbane, said the fine and the order to repay underpaid workers would be meaningless if the franchise declares itself bankrupt.

"There is a significant fine but if the owner of the store decides to declare bankruptcy, it will be meaningless. No one will get paid," he said.

"Head office needs to step in and guarantee the payments will be made.

"If head office doesn't step in to do something about it, workers are at risk of winning the battle but losing the war."

Mr Sivaraman said he hoped the record $400,000 penalty would deter other 7-Eleven franchises from continuing to exploit workers. However, he feared workers were vulnerable to being exposed.

He said his firm had in recent years successfully prosecuted a 7-Eleven franchise for under-paying its workers and the franchise was fined and ordered to backpay workers.

"It then declared bankruptcy and avoided making any of the payments," he said. "The workers were left without anything.

"My question is, what is to stop that happening here."

Mr Sivaraman said he was also concerned about the potential for 7-Eleven franchises to go into bankruptcy and start a new business to escape liability – a practice known as phoenixing.

Earlier this year, Maurice Blackburn called for the introduction of new laws to make franchisors including 7-Eleven and Pizza Hut responsible for the conduct of franchisees who breach workplace laws by underpaying workers and entering sham contracting arrangements.

Maurice Blackburn employment principal Josh Bornstein said in April it was time to stop "franchisors turning a blind eye to systemic wage fraud undertaken across their franchise networks".

7-Eleven chief executive Angus McKay said on Tuesday it had taken the wage repayment program process in-house "to deliver a robust and efficient process that puts money in the hands of claimants as quickly as possible".

"We have spent the past few weeks building a claims assessment process that places legitimate claimant interests at its centre and responds to feedback from all key stakeholders," he said.

"We are confident that our wage repayment process delivers against these objectives, and are now absolutely focused on ensuring it meets our commitment to pay legitimate claims as quickly as possible.

"7-Eleven is happy to be judged on our actions, and will continue to publicly report our progress as we move forward."

7-Eleven has also encouraged any former or current Franchisee staff who believe they have not been paid their full entitlements to come forward and submit their claim to the Secretariat on 1800 619 802 or www.wagerepaymentprogram.com.au.