Optus is facing a class-action style claim over the data breach in which personal information on almost 10 million Australians was stolen, with national law firm Maurice Blackburn lodging a representative complaint with the privacy watchdog.

The complaint to the Office of the Australian Information Commissioner (OAIC), which also deals with privacy breaches, is similar to a class action claim in court and allows the commissioner to order compensation en masse to affected people if breaches of privacy law are identified.

Australia's privacy regime has 13 principles, including a requirement for organisations such as Optus to "take reasonable steps to protect personal information... from misuse, interference and loss, and from unauthorised access, modification or disclosure."

Maurice Blackburn said in a written statement that the claim would be a test of privacy laws. "The representative complaint alleges Optus failed to protect the personal information of its customers and ensure the destruction of information that it no longer needed," its statement reads.

Macquarie University academic Sean Foley, who left Optus as a customer in 2017, but had his personal details including document numbers taken in the breach is the representative complainant, according to Maurice Blackburn.

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An Optus spokesman said: “We will vigorously defend any representative complaints.”

The telco has consistently defended its cybersecurity practices and emphasised that the nature of the breach is still under investigation by authorities and consultants at Deloitte. It has given customers a year of free credit monitoring and in some states is reimbursing the cost of licence replacements for those affected with credit on their accounts.

Unlike other countries, Australia does not let people sue in court directly for privacy breaches.