A judge has slammed Optus for trying to keep secret a report into the causes of its 2022 cyberattack, putting further pressure on chief executive Kelly Bayer Rosmarin to be more transparent after coming under attack for her handling of this week’s communications outage.

Federal Court Justice Jonathan Beach ruled on Friday afternoon that Optus had “not made good their claim of privilege” over a review Optus had told the public was to help others understand what went wrong so they could avoid similar attacks. The effort to produce the report, involving Optus, consultants Deloitte and lawyers Ashurst, was known internally as “Project Amsterdam”.