ACC has referred a former staff member to the Serious Fraud Office (SFO) after the organisation discovered improprieties.
"While investigating a staff member's failure to follow internal policies and procedures other matters of concern were uncovered," ACC chief executive Jan White said today.
"Owing to the nature, potential scale and duration of those matters we believed it was appropriate to refer them to the SFO."
ACC would now wait until the SFO told them if a formal investigation was warranted.
The staff member had been dismissed for failing to follow policies and procedures.
Dr White said the ACC board had told ACC Minister Nick Smith of the issue.
The State Services Commission, Department of Prime Minister and Cabinet, Department of Labour and Auditor General had also been informed.
"Given that this situation is being considered by the SFO, ACC will not be making any further public comment at this stage," Dr White said.