Maurice Blackburn Lawyers, Bannister Law Class Actions and Centennial Lawyers have united to run the data breach complaint against Medibank which they say could secure compensation for as many as 9.7 million affected customers.

Data from millions of current and former Medibank customers was hacked in October, with the Russian ransomware group behind the breach releasing the information in stages onto the dark web.

The three law firms have been investigating compensation claims and say they have already registered tens of thousands of Medibank customers.

Last November, Maurice Blackburn lodged a formal complaint against Medibank with the Office of the Australian Information Commissioner (OAIC), which has the power to order compensation.

Under the firms’ co-operation agreement, they will now pursue the OAIC complaint seeking compensation for those affected by the data breach.

Bannister Law Class Actions principal Charles Bannister said he hoped the co-operation agreement would lead swiftly to compensation payments to the millions of Medibank customers whose data was breached.

“We believe the data breach is a betrayal of Medibank Private’s customers and a breach of the Privacy Act. Medibank has a duty to keep this kind of information confidential,” Bannister said.

Maurice Blackburn’s head of class actions Andrew Watson said the cooperation agreement was a significant development.

“This data breach has caused millions of Australians significant distress,” he said.

“The co-operation agreement ensures that all three law firms are working together for the common aim of obtaining compensation for those affected as quickly as possible.”

A Medibank representative said the company was continuing to cooperate with the OAIC.

“Medibank continues to support its customers from the impact of this crime through our previously announced Cyber Response Support Program which includes mental health and wellbeing support, identity protection and financial hardship measures,” the representative said.

– AAP