Telstra has been forced to reset 230,000 passwords after its gaming website GameArena and online gaming shop were hacked.
Up to 35,000 usernames, email addresses and encrypted passwords for the site were thought to be compromised but Telstra said it was resetting the majority of passwords as a precaution.
Those affected were largely those using non-BigPond email addresses, according to the telco.
Financial or credit card data was not stored on the third party-hosted sites.
Telstra was re-issuing new passwords to users and has warned customers to reset affected passwords that were re-used on other sites.
GameArena was developed by Brisbane-based Mammoth Media.