The error was put down to a third-party provider, Business Information Services, with the department's chief financial officer claiming the leak "is not a result of any of the department’s internal systems”.
The Guardian reported that the department had sent letters to the affected employees earlier this month, alerting them to the compromise within the credit card management system.
It said the data that was exposed included credit card details, names, usernames, work phone numbers, work emails, system passwords, Australian Government services numbers, public service classifications and organisation units.
The newspaper quoted a spokesperson from BIS as saying there was no evidence of a cyber attack.
The information that leaked included “partially anonymous work-related expenses”. Also “cost centres, corporate credit cards without CCV and expiry dates and passwords that were hashed and therefore not visible”, were visible during the 16 months that the data was exposed.