Some 7-Eleven employees have been back-paid up to $400,000 each but the company is axing the independent panel set up to judge more claims.
Professor Allan Fels was hand-picked to run an independent process reimbursing workers after it was revealed some franchisees systematically underpaid international students on threat of deportation.
But he now says 7-Eleven's management has "welshed" on public promises to pay staff back after he was sacked as an independent judge of workers' claims.
"One of the red lights for 7-Eleven was the fact that some individual claims have been up in the hundreds of thousands," Prof Fels said on Wednesday night.
"There have been some claims of the level $350,000 (to) $400,000."
Prof Fels said 7-Eleven applied "great pressure" on the panel not to reveal those amounts to the public, and in the interest of keeping the relationship going, the panel agreed.
So far about 400 employees have been paid a combined $12 million, with more than 2000 cases still to be assessed.
Professor Fels' panel will stop its work on Friday, and all existing and new wages claims will be handled by an independent unit within 7-Eleven.
"It is important to state unequivocally that the process for claims will continue and 7-Eleven will pay all legitimate claims by franchisee employees for the past underpayment of wages," chairman Michael Smith said in a statement earlier on Wednesday.
"Ethical corporate standards cannot and should not be outsourced. We are happy to be held to the standards we have set for and expect of ourselves."
But Prof Fels said the decision showed 7-Eleven was trying to minimise the payouts.
Prime Minister Malcolm Turnbull said the underpayments issue was a big one.
"We are going to make sure the law is enforced," he told reporters in Melbourne.
