Australia’s communications watchdog has launched legal action against Optus after the massive data breach that affected 10 million people.

The Australian Communications and Media Authority announced it had filed proceedings in the Federal Court against the Singapore-owned telco on Friday.

“We allege that during a data breach which occurred between 17 to 20 September 2022, Optus failed to protect the confidentiality of its customers’ personal information from unauthorised interference or unauthorised access,” the watchdog said in a statement.

“As this matter is now before the court, the ACMA will not be making any further statements at this time.”

Optus suffered a huge breach in 2022 that affected 10 million Australians and resulted in the driver’s licences, Medicare and passport numbers of 10,000 customers being stolen and leaked online.

Optus said it was unable to determine the penalties that could arise from the legal action.

“Optus has previously apologised to its customers and has taken significant steps, including working with the police and other authorities, to protect them,” a statement from the company said.

“It also reimbursed customers for the cost of replacing identity documents. Optus intends to defend these proceedings. As the matter is now before the courts, Optus is unable to make any further comment.”