Coles’ wages scandal has blown out, with the supermarket giant revealing it has more than doubled since it was uncovered.

The retail chain revealed on Friday that the pay and allowances shortfall first identified more than three years ago had increased by an expected $25 million.

Coles first admitted in 2020 that a company-wide review had found it owed $20 million in unpaid wages and other payments to managers of its supermarkets and liquor division over six years. After the latest announcement, the total bill for the shortfall has reached $45 million.

Coles Group “unreservedly apologised” to affected employees in a statement to the Australian Stock Exchange.

“In February 2020, Coles announced it was conducting a review into the pay arrangements for all salaried team members covered by the General Retail Industry Award after identifying shortfalls,” the statement said.

“Coles expressed its deep regret and apologised to affected team members.”

Coles has faced a class action and legal action by the Fair Work Ombudsman over the staff underpayments.

“Coles has continued to work diligently in relation to these issues,” the company’s statement said.

“Coles advises that, following further consideration of the issues as they have evolved, it intends to conduct a further remediation relating to the reconciliation of available records of the days and hours of work of salaried supermarket managers.

“Coles will take an additional provision of $25 million in relation to this matter.”

The company is still awaiting a court decision on other “complex issues” relating to the case.

Coles’ update came just a day after mining giant BHP admitted it had underpaid nearly 30,000 workers by a mammoth $430 million over more than a decade.

“A preliminary review suggests that certain rostered employees across our Australian operations have had leave incorrectly deducted on public holidays since 2010,” it said on Thursday.

“There are approximately 28,500 affected current and former employees with an average of six leave days in total that have been incorrectly deducted from affected employees over this 13-year period.”

BHP said the error amounted to 170,000 days across the company.

“It is estimated that the cost of remediating the leave issue and the contracting issue will be up to $US280 million ($431 million), incorporating on costs including associated superannuation and interest payments,” it said.

The company’s Australian president, Geraldine Slattery, apologised to affected staff.

“This is not good enough and falls short of the standards we expect at BHP,” she said.

“We are working to rectify and remediate these issues, with interest, as quickly as possible.”

BHP said it would contact affected current and former employees to alert them. A dedicated hotline and website will be running from Friday.

Coles and BHP are just the latest a string of household Australian names to report underpayment of wages and other entitlements in recent years.

Supermarket competitor Woolworths has admitted to more than $600 million in underpayments over recent years, including $70 million in February. Another rival, Wesfarmers – owner of Kmart, Target and Bunnings – has also revealed millions in “payroll errors”.

Super Retail Group – the owner of Supercheap Auto, Rebel Sport, Macpac and BCF – is accused of underpaying workers by more than $1 million.

In May, Mosaic Brands – Australia’s largest speciality fashion retailer – copped a $29,000 fine for underpaying long-service leave entitlements.

Mosaic Brands, which has 1100 stores, including brands Millers, Rivers, Katies, Rockmans and Noni B, pleaded guilty to 324 offences in Sydney’s Downing Centre Local Court. It was fined on May 19.