Australia's Westpac Banking Corp on Friday said it will have to pay A$8 million ($5.5 million) to around 8,000 employees who were found to have been underpaid their long-service leave entitlements due to calculation errors.

The admission from the country's second-largest lender follows a string of underpayment scandals by some of Australia's biggest companies including Wesfarmers Ltd and supermarket chains Coles Group and Woolworths Group.

That had prompted the federal government to say it would introduce tougher laws that criminalise what it called "wage theft" and ban executives from being company directors if they were involved.

Westpac said in a statement that calculation errors, which had led to underpayment and overpayment, were identified as part of its payroll review and long service leave arrangements.

According to Australia's labour laws, an employee gets long-service leave after a long period of working for the same employer.

The lender added that it will not ask anyone who has been overpaid to repay any money.

"We apologise to anyone impacted by these errors and our priority is to make payments as soon as possible," Alastair Welsh, Group Executive, Enterprise Services said.

"We are putting in place measures to ensure employee long service leave is correctly calculated."

(Reporting by Shriya Ramakrishnan in Bengaluru; Editing by Shri Navaratnam and Michael Perry)