Almost 50,000 affected by data breach

The personal details of almost 50,000 Australian workers have been exposed online by a third-party contractor.

The data breach, first reported by iTnews, disclosed the names, passwords, phone numbers, email addresses, credit card numbers and salaries of workers across government agencies, banks and insurer AMP.

An AMP spokesman confirmed "a limited amount of company data" on staff expenses was inadvertently exposed by a third-party supplier.

"The mistake was quickly corrected once identified and the matter investigated to ensure all data had been removed. No customer data was compromised at any time," the spokesman told AAP on Thursday.

"AMP treats data security very seriously and has strict policies in place regarding the handling of data with third party vendors. We are reviewing the situation to ensure standards are maintained."

The Australian Cyber Security Centre (ACSC) was alerted to the breach in the first week of October and immediately contacted the external contractor to secure the information and remove the vulnerability within hours of notification.

A Department of Prime Minister and Cabinet spokeswoman said the exposed data did not contain any national security information, classified material, or Australian government customer data.

"The data exposed was historical, archived and partially anonymised data," she said.

The departments involved had been notifying affected staff and working to give them appropriate support, she said.