The outgoing director of Australia's spy agency has labelled foreign interference and espionage "by far and away" the most serious - and potentially existential - contemporary threat to the country.
ASIO director general Duncan Lewis will this month stand down from the role after a five-year term, handing over to Mike Burgess.
At an address at the Lowy Institute on Wednesday, Mr Lewis said there were three "threat vectors" that dominate the organisation's work - foreign interference and espionage, terrorism and cybersecurity.
But it was the former that concerned him most, notwithstanding the 2018 passage of laws aimed at preventing foreign influence on Australian politicians, media, ethnic groups and civil society organisations.
Mr Lewis repeated his previous declaration that the extent and scale of foreign interference threats to Australia was unprecedented.
"A place like Australia, terrorism is not an existential threat to the state - it is a terrible risk our populations run and it's a very serious matter," Mr Lewis said.
"The counter-espionage and foreign interference issue, however, is something which is ultimately an existential threat to Australia, or can be an existential threat - it has the capacity to do that.
"The harm from acts of espionage may not present for years or even decades ... these sorts of activities are typically quiet, insidious and have a long tail."
Espionage, treason and treachery offences were all expanded under the 2018 legislation, while acting with a foreign country to influence Australia's democracy was criminalised with penalties of up to 20 years' jail.
Mr Lewis also said authorities were "getting a better understanding" of the threats posed in cyberspace and actors in that sphere.
Under questioning, Mr Lewis said foreign interferers - whether state or non-state actors - had been facilitated by the ease and immediacy of technological advances such as internet and social media.
"You do it because you can - communities and countries are able to interfere in one another's business now because you can," Mr Lewis said.
While he declined to point to particular actors, China's increasing military might and Pacific presence have concerned Australian lawmakers, who last month also pledged to crack down on Australian university interference.
Mr Lewis insisted his organisation was trying to find the "sweet spot" between passivity and overreaction and also avoid the vilification of minorities, such as Muslim Australians or Chinese-Australians.
He said he had previously spoken to politicians about tempering their rhetoric on minority groups to preserve community relationships.
Australian Associated Press