Australia's government and institutions are being targeted by ongoing sophisticated state-based cyber hacks, Prime Minister Scott Morrison says.
Scott Morrison said the "malicious" activity had been increasing over months
Mr Morrison said the cyber attacks were widespread, covering "all levels of government" as well as essential services and businesses.
He declined to identify a specific state actor and said no major personal data breaches had been made.
The attacks have happened over many months and are increasing, he said.
The prime minister said his announcement on Friday was intended to raise public awareness and to urge businesses to improve their defences.
But he stressed that "malicious" activity was also being seen globally, making it not unique to Australia.
Who has been targeted?
Mr Morrison did not name specific cases but said it had spanned "government, industry, political organisations, education, health, essential service providers and operators of other critical infrastructure".
He did not give further details. Previously, defence manufacturers, government contractors and accounting firms have been among those to report data breaches.
Last year, the Australian National University said it had been hacked by a sophisticated operation which had accessed staff and student details.
Australia's main political parties and parliament were hit by a "malicious intrusion" earlier in 2019, also attributed to a "sophisticated state actor".
Who is behind it?
Speaking on Friday, Mr Morrison said officials had identified it as a state hack "because of the scale and nature of the targeting and the trade craft used".
"There are not a large number of state-based actors that can engage in this type of activity," he said, without giving specifics.
When asked to identify a country, Mr Morrison said he would not make "any public attribution".
Cyber intelligence experts have long linked various hacks in Australia to China.
They say China is one of the few states, along with Russia, Iran, and North Korea, which have the capacity for such attacks - and are not allied with Australia. However, they also note that cyber espionage between countries and even allies is common.
"There's always simmering tensions between Russia and China so really it comes down to those being the key actors they [Australia] would be referring to," expert Joshua Kennedy-White told the BBC.
The Reuters news agency has previously reported that Australian intelligence agencies suspected China of carrying out the parliament hack in 2019. Canberra declined to comment. BBC