The Australian Security Intelligence Organisation has paved the way for increased public preparedness to defend Australia’s sovereignty against foreign interference, outgoing ASIO head Duncan Lewis has said.

In an address to the Lowy Institute, Lewis repeated his earlier warning about this interference. “The current scale and scope of foreign intelligence activity against Australian interests is unprecedented,” he said.

While the threat was not just from any one particular country, Lewis noted the scale and sophistication of threats varied greatly.

He did not mention China by name, but the government considers China poses by far the largest threat in terms of interference on a range of fronts.

Some years ago Lewis warned the major political parties of this attempted influence through political donations. In the current NSW ICAC inquiry attention has been centred on an alleged $100,000 donation to Labor in 2015 by Chinese property developer Huang Xiangmo, a banned donor. Huang later was prohibited from re-entering Australia, on ASIO advice that he had links with the Chinese Communist Party.

Lewis warned that “unlike the immediacy of terrorism incidents, the harm from acts of espionage may not present for years, even decades, after the activity has occurred. These sorts of activities are typically quiet and insidious, with a long ‘tail’”.

“There has been a great deal of coverage recently in the Australian media regarding espionage and foreign interference, ascribing blame and describing vectors of attack and influence.

"It is not proper for me to dive into the detail of this coverage for a number of reasons.

"Suffice it to say I am satisfied that ASIO is following the ball closely and has seeded what is now a public consciousness and awareness of the matter and I hope in short-order there will come an increased public preparedness to better defend our country and its sovereignty,” Lewis said.

Read more: New ASIO head, Mike Burgess, is moving from one security agency to another

On terrorism, he said the global threat from violent Islamist extremism was not eliminated by ISIL’s declining fortunes and loss of terititory.

“Increasingly, disillusioned ISIL supporters are turning to more egregious and desperate measures in and beyond the Middle-East.”

On the “complex” issue of returning foreign fighters, “we have worked to develop and implement effective and appropriate management strategies. We will be paying a lot of attention on a case by case basis to the security implications of any returnees with a range of responses”.

These varied, “depending on whether the returnee is an active foreign fighter, where a successful brief would see them in jail, or whether the case is of an infant who clearly would be approached in a completely different way,” Lewis said.

“At the other end of the spectrum, right wing or ethno-supremacist extremism is not being ignored by ASIO.

"Recent history around the world is peppered by acts of extreme right wing motivated attack”, including the horrific Christchurch massacre, Lewis said.

The new chief of ASIO is Mike Burgess, former head the Australian Signals Directorate.