Optus has not yet told Services Australia about the customer information that was stolen.
In the wake of its major data leak, the government says Optus has not been working with them. Australians are being told to be careful.
A federal government minister said that Australia needs to change its cyber security rules to prevent another leak like Optus's latest nightmare.
The telco has been criticized for not working with the government after the breach because it hasn't given the full list of customers who were affected.
Minister for Cyber Security and Home Affairs Clare O'Neil said on Sunday that we need to think about what companies have to do when a cyber attack like this happens.
"We just don't want to go through this again. The private information of 10 million people has been kept by a private company for far too long, and we don't have the right tools to get information in certain ways after the fact. It doesn't cut it."
"We live in a digital age, so cyber security issues are a part of our lives now. This incident is a huge wake-up call to corporate Australia... It's also a wake-up call for ordinary Australians.
"We just need to make a big change in how we protect our computers in this country."
Ms. O'Neil went on to say that Australians whose information was leaked should be aware that some people may now try to use it to their advantage.
"Australians need to be very careful right now. We shouldn't be in this situation, but Optus put us here, and now Australians need to take steps to protect themselves from financial crime," she said.
The warning comes after it was found out that Optus has not yet given a major government agency all of the details about the customers whose information was stolen in its huge data breach.
Bill Shorten, Minister of Government Services, made the new request on Sunday morning, more than a week after the wide-ranging incident in which the information of 10 million Australians was accessed.
Services Australia wrote to Optus on September 27 and asked for the full list of all affected customers whose Services Australia credentials were exposed.
Some of these were Medicare cards and Centrelink Concession Cards.
Services Australia said that Optus had not given any information about customers who would be affected by this request.
Mr. Shorten said that Australians caught up in the saga should be able to keep their privacy.
"Services Australia has been working around the clock to protect customers, but we need Optus to help us help Australians," he said.
"This was a mistake that shouldn't have been made."
"Everyone in Australia has a Medicare card in their wallet, so it's not surprising that they are very worried about what's going on here."
It comes a few days after Optus said it would pay for Australians whose passports were stolen in the cyber attack to get new ones.