Medibank says it has been notified by the plaintiff law firm Maurice Blackburn that it lodged a representative complaint with the Office of the Australian Information Commission (OAIC).
Medibank said the OAIC has not yet contacted it about the complaint.
"The complaint includes allegations that Medibank has breached the Australian Privacy Principles and seeks compensation for individuals whose personal information was exposed as a consequence of the cybercrime," said the company.
"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," it added.