The prime minister's department has not taken any action over reports Malcolm Turnbull and government ministers have been using the message service WhatsApp to communicate.
Labor says the use of the app treats government security with contempt.
But Department of Prime Minister and Cabinet deputy secretary Elizabeth Kelly told a Senate estimates hearing on Monday the issue had not been followed up because the prime minister had made "numerous public statements about the appropriate use of this".
Attorney-General George Brandis confirmed he had communicated with the prime minister and other ministers using WhatsApp.
Asked by senior Labor figure Penny Wong what was the nature of the communication, Senator Brandis said: "Nothing of public sensitivity ... it is entirely unremarkable."
There had "never been an occasion" when WhatsApp had been used by ministers for anything but "material of an extremely routine nature".
The prime minister's cyber security adviser Alastair MacGibbon said he also used WhatsApp to contact Mr Turnbull.
"It might be something like 'could you call me'," he said of the messages.
Senator Brandis said it was possible WhatsApp messages could be discovered via Freedom of Information requests.
"The FOI Act is platform neutral," he said.
The committee was told there were no specific guidelines on the use of WhatsApp and other similar messaging applications other than a requirement for ministers and officials to keep in mind the security classification of official information.
The prime minister's cyber security adviser Alastair MacGibbon said no advice had been provided by the Australian Signals Directorate until the issue was raised in the media over the weekend.
He said he was not concerned about ministers' communications using WhatsApp as it appeared it was only being used for unclassified information.
Asked whether he had done any investigation to confirm no classified information was being exchanged, he said: "No, I have not."
