The data breach has put 9.8 million customers at risk, with hackers already releasing 10,000 private records on Tuesday.

"People are rightly concerned that if a criminal has access to personal information, they may be subject to identity theft," a Slater and Gordon spokeswoman told ACM.

"Vulnerable members of the community, such as people who are survivors of domestic violence and victims of stalking and other threatening behaviour, are concerned perpetrators may be able to use the information to locate them."

IN OTHER NEWS

Small businesses have told the law firm they've had to suspend activity on credit accounts, and people are frustrated by the difficulty in changing personal information.

"While class actions involve complex issues of law, we know that affected customers are extremely concerned and we are working as quickly as possible to investigate potential legal options," the spokeswoman said.

With an investigation into the matter underway, Slater and Gordon declined to say when or if the class action will be launched.

Former and current Optus customers can continue to register for the class action at www.slatergordon.com.au/optus.