Tanya Plibersek said while people had been receiving their bills on time, the telco had not told customers whether their personal details have been stolen.
"One of the real problems is the lack of communication by Optus, both with its customers and the government," she told the Seven Network.
"I don't think the company is doing a particularly good job with its customers or providing the government with the information we need to keep people safe.
"It's extraordinary we don't have any Medicare numbers or Centrelink numbers that may have been compromised."
Nationals MP and former deputy prime minister Barnaby Joyce said Optus had "compromised their capacity to do their job".
"Those in the know say it wasn't a very sophisticated way to get into the Optus information," he told the same network.
Mr Joyce questioned why the telco had "been so lax" about the data breach.
"Why can't they protect your privacy and get back to people and say we have a real problem here and be careful?" he said.
Optus was also slammed by Albanese government ministers for not responding to its requests for information to help protect almost 10 million Australians from fraud at a press conference on Sunday.
Services Australia wrote to Optus on Tuesday asking for the full details of all customers who had their Medicare cards or Centrelink Concession Cards compromised to boost security measures.
The government said Optus was yet to respond to the request.
At least 10,000 parcels of ID data taken in the breach, were put on the internet for sale by the hacker, before they took it down.
Cyber Security Minister Clare O'Neil said Optus needed to be up-front about what specific data had been taken for individuals, while admitting the government didn't know how many passport numbers had been stolen.
"Optus advised me this morning that they have contacted the 10,200 people, I gave very clear feedback to Optus that an email was not going to cut it here," she said.
Ms O'Neil said the government was particularly concerned for those people whose sensitive data had already been published in the "ether".
Government Services Minister Bill Shorten said about 36,900 Medicare numbers had been leaked.
He said Services Australia was ready to act and begin flagging individuals and their accounts, but the government needed Optus to reveal who had been caught up.
Optus chief executive Kelly Bayer Rosmarin has apologised to customers, but is resisting calls to step down following the disaster.
Ms O'Neil criticised the former Morrison government, describing laws designed to protect Australia's critical infrastructure from cyber attacks as "absolutely useless".
"This company (Optus) has just overseen what is without question, the largest consumer data breach in Australian history," she said.
Opposition cyber security spokesman James Paterson said the coalition would be open to bigger fines for breaches of the Privacy Act.
In a statement, an Optus spokesperson said the company was working with government agencies to determine which customers it needed to take action on.
"We continue to seek further advice on the status of customers whose details have since expired. Once we receive that information, we can notify those customers," the spokesperson said on Sunday.
"We continue to work constructively with governments and their various authorities to reduce the impact on our customers."
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