Vodafone said today that it is aware of only the single breach of its customer credit card numbers, phone logs and personal details, detailed by Fairfax.
The telco fell into hot water following allegations that criminals had been sold access to its sensitive customer database and planned to use the information, which includes voice and SMS logs, to blackmail customers.
The publication reported that other people had obtained the internal log-in to check their spouse's communications.
Vodafone said it will have confirmation whether details have been leaked after a preliminary report is finalised today, but noted the detailed findings may not "necessarily" be made public.
"[The Fairfax report is] the only instance that we know of at this stage. We are conducting a full investigation and we will see what that uncovers," Vodafone spokesperson Greg Spears said.
"We are reticent to talk about it because we don't know if it was a dealer or one of our retail staff. It is an allegation of a one-off instance."
Chief executive Nigel Dews told the ABC the alleged breach "could be someone who works in our stores or one of our dealers".
"If that's the case, we will come down with the full force of the law."
The Australian Federal Police told ZDNet Australia that it had not yet received a referral to investigate the matter.