Tech giants Facebook and Apple say they will resist the Turnbull government's push for them to decrypt messages and hand them over to law enforcement agencies, as they already provide as much help as they can.
Prime Minister Malcolm Turnbull on Friday said technology companies such as Facebook and Apple need to "face up to their responsibility" to help prevent terrorism and solve crimes.
Acknowledging "this is not without some difficulty", Mr Turnbull said the government would legislate to force companies to provide encrypted communications requested by the police and other agencies.
"What we're seeking to do is to secure their assistance," Mr Turnbull said at a media conference in Sydney.
"They can't just, you know, wash their hands of it and say it's got nothing to do with them. So we need - what we need to do is to secure their co-operation."
A Facebook spokeswoman told Fairfax Media: "We appreciate the important work law enforcement does, and we understand their need to carry out investigations.
"That's why we already have a protocol in place to respond to requests where we can.
"At the same time, weakening encrypted systems for them would mean weakening it for everyone."
Facebook also owns the popular messaging service WhatsApp, which uses end-to-end encryption and says "privacy and security is in our DNA".
Facebook last month posted an official statement saying it was not capable of reading encrypted messages.
"Because of the way end-to-end encryption works, we can't read the contents of individual encrypted messages - but we do provide the information we can in response to valid law enforcement requests, consistent with applicable law and our policies," the statement by Facebook's director of global policy management and counterterrorism policy manager said.
"We know that terrorists sometimes use encrypted messaging to communicate.
"Encryption technology has many legitimate uses - from protecting our online banking to keeping our photos safe.
"It's also essential for journalists, NGO workers, human rights campaigners and others who need to know their messages will remain secure."
An Apple spokeswoman pointed Fairfax Media to a statement saying: "We believe security shouldn't come at the expense of individual privacy."
"For all devices running iOS 8 and later versions, Apple will not perform iOS data extractions in response to government search warrants because the files to be extracted are protected by an encryption key that is tied to the user's passcode, which Apple does not possess," the statement says.
After a terrorist attack in San Bernadino, California, that killed 14 people in 2015, Apple refused to help the FBI break into a phone to access data.
Asked whether the laws of mathematics behind encryption would trump any new legislation, Mr Turnbull said: "The laws of Australia prevail in Australia, I can assure you of that.
"The laws of mathematics are very commendable but the only law that applies in Australia is the law of Australia."
Australian Federal Police deputy commissioner Mike Phelan said legislation had not kept pace with technology and police investigations were being hampered by an inability to read encrypted communications.
"The vast majority of our investigations, indeed 65 per cent of our serious and organised crime investigations, counter terrorism investigations, major paedophile investigations, now involve some sort of encryption," he said.
Opposition Leader Bill Shorten backed the government's push, saying "we're all in this together" on combating terrorism.
"With terrorism being a 21st Century conflict, we need 21st Century weapons to deal with it," he said.
"The big tech giants have a position of privilege in our society, so it is appropriate that they contribute to the safety and wellbeing of Australian society."
Shadow attorney-general Mark Dreyfus struck a more cautious tone, saying: "We will wait to see the detail on how the government's proposal will actually work because that wasn't forthcoming today.
"We are concerned Mr Turnbull was unable to answer repeated, specific questions about how the government's proposals will work in practice."
Mr Turnbull's special adviser on cyber security, Alistair MacGibbon, said the government was simply asking technology companies to "live up to the moral obligations to protect the public".
"Why is it for some reason considered wrong or obnoxious that the hi-tech industry, the industry that affects so much of our lives, doesn't actually have that same level of obligation to help protect its own customers?"
Advocacy group Digital Rights Watch said: "This is a worrying move from the government that could have far-reaching impacts into digital security, freedom of speech, and the necessary protection of individual's privacy."