The ABC is apologising to thousands of casual employees who were underpaid because of a payroll error.

More than 2000 employees have been affected over the past six years.

A test, done by the Community and Public Sector Union, found one staff member was underpaid by $19,000.

The national broadcaster says the mistake relates to calculating penalties, allowances and loadings.

The Fair Work Ombudsman is investigating.

The Union’s Sinddy Ealy tells Ross Greenwood it’s unacceptable.

“There are a number of hardworking ABC staff, including managers who are being provided with advice that the payment arrangements were kosher, clearly they’re not.

“The people who were responsible for providing that advice should absolutely be held to account for their negligence.”

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