Optus is set to defend Federal Court action brought against it by the regulator, the Australian Communications and Media Authority (ACMA), over a September 2022 data breach that saw personal data stolen from around 10 million current and former customers.

The regulatory body alleges that Optus failed to safeguard its customers' personal information during the data breach, which was one of the worst in the nation's history. Data accessed included home addresses, passport numbers and phone numbers of customers.

"Optus failed to protect the confidentiality of its customers’ personal information from unauthorised interference or unauthorised access as required under the Telecommunications (Interception and Access) Act 1979 (Cth)," the ACMA alleged in a statement. The regulatory body has said it will not be making anu further statments now that the matter is before the Court.

It comes as the telecommunications business yesterday posted its results for the full year ended 31 March 2024, delivering 'stable' growth compared to the previous year, with EBITA up 0.7 per cent to $2.103 billion.

Interim CEO and CFO Michael Venter said the results demonstrated a solid performance in a difficult environment, as Optus remained focussed on enhancing customer experience.

“Optus is working hard to rebuild the trust of customers after a challenging 18 months and these results demonstrate we are on the right track,” Mr Venter said.

“We’re listening to our customers and in the year ahead we’ll be continuing to prioritise what we know is important to them – a resilient network that delivers seamless connectivity, great value products and services, and simple, efficient customer service.”