Medibank is facing legal action over a data security breach last year in which personal information of thousands of customers was stolen.
A class action lawsuit was filed against the company in the Federal Court on Tuesday by international law firm Baker & McKenzie.
"Medibank understands that these proceedings have been brought on behalf of current and former customers in relation to the cybercrime event Medibank has previously reported," the company said.
The claim includes allegations of breach of contract, contraventions of the Australian Consumer Law and breach of equitable obligations of confidence, according to a statement by Medibank.
Medibank said it plans on defending the claims.
Several other law firms flagged their intentions earlier this year to file similar actions against Medibank, including a conglomerate involving Maurice Blackburn Lawyers, Bannister Law Class Actions and Centennial Lawyers.
At the time, the firms claimed to have already registered tens of thousands of Medibank customers and said the action could secure compensation for as many as 9.7 million.
Medibank said it was continuing to support affected customers through its Cyber Response Support Program which includes mental health and wellbeing support, identity protection and financial hardship measures.
Australian Associated Press