One of the nation's biggest banks has been accused of ripping off thousands of its part time workers.
The Commonwealth Bank could owe "millions of dollars in back payments plus interest" in missed superannuation entitlements, the Financial Sector Union says.
The union on Tuesday said at least 7000 workers, mostly women, could be affected and that the issue dated back to 2009.
"They have been paid superannuation to cover the hours they were originally contracted to work for, not the actual hours worked," national secretary Julila Angrisano said.
"CBA workers are telling us that they frequently work longer hours to cover staff shortages."
The FSU also said it had a legal opinion that the bank should be paying "9.5 per cent extra" into superannuation accounts for members to cover their full weekly wage.
CBA employs part-time workers in its branches, call centres and administration areas.
The bank said it was reviewing FSU's claims and was committed to ensuring it complied with its obligations to employees.
"[We] have assured them that CBA understands the importance of superannuation to help secure and enhance the financial wellbeing of our employees," CBA said in a statement.
