Australian mining giant BHP says it has been underpaying current and former workers across the country for 13 years.

Meanwhile, 400 workers did not receive additional benefits “due to the fault of the employer.”

BHP said it had reported the incident to authorities and that the errors would cost the company up to $280 million (£225 million) before taxes.

The company says some affected employees have had their wages deducted incorrectly on Australian holidays. As a result, on average they were owed a total of six days of leave.

“We apologize to all current and former employees affected by these lapses. This was not good enough and did not meet the standards we expected at BHP,” said Geraldine Slattery, Chairman of BHP Australia, said.

“We are working to fix and fix these issues, with care, as quickly as possible,” she added.

The company also said it has conducted a review of its pay system. It added that it will provide an update on its surveys during its full-year earnings call in August.

BHP, based in Melbourne, is the largest mining company in the world.

It has about 80,000 employees and contract workers at sites including the Escondida mine in Chile, which is the largest copper mine in the world.

In addition to its Australian-listed stock, the company has been part of the UK’s FTSE 100 blue chip index for about a decade.

In January 2022, the company withdrew its shares from the London market after coming under pressure from some investors to simplify the company structure.

Proponents of the move argue that it will make it easier for BHP to raise money, execute transactions, and return money to shareholders.