SYDNEY:Australia on Monday raised its terrorism threat level to "probable", with the country's top intelligence official citing a homegrown rise in "extreme ideologies."

Intelligence chief Mike Burgess said there was no indication of an imminent attack, but there was an increased threat of violence in the next 12 months.

"Australia's security environment is degrading, is more volatile and more unpredictable," Burgess told reporters.

"You've heard me say many times that espionage and foreign interference are our principal security concerns... intelligence suggests that is no longer accurate.

"Politically motivated violence now joins espionage and foreign interference as our principal security concerns."

Burgess, the head of the Australian Security Intelligence Organisation, said more Australians were being radicalised and they were increasingly willing to use violence to advance their cause.

"Individuals are embracing anti-authority ideologies, conspiracy theories and diverse grievances. Some are combining multiple beliefs to create new hybrid ideologies," he said.

Australia's threat level had until Monday been classified as "possible."

Burgess said extreme ideologies had increased during the Covid-19 pandemic, and more recently during the Israel-Hamas conflict.

"An escalation of the conflict in the Middle East, particularly in southern Lebanon, would inflict further strain, aggravating tensions and potentially fuelling grievances," he warned.

In the past four months, eight "attacks or disruptions" had alleged or potential terror links, he said, declining to comment on them in detail.

In one high profile attack in April, a 16-year-old boy allegedly stabbed an Assyrian Christian bishop during a live-streamed Sydney church service.

Burgess said none of the terror plots investigated by ASIO in the past year had been inspired by events in Gaza, although the conflict had an impact by fuelling grievances, protests, division and intolerance.

"It would also be inaccurate to suggest the next terrorist attack or plot is likely to be motivated by a twisted view of a particular religion or a particular ideology," he said.

"The threat is across the board."

The spy chief said social media and encrypted apps were making the threats "harder to predict and identify."

The internet and social media were "the primary platform for radicalisation and the use of encryption by every single one of our investigative subjects," he said.

In the new threat landscape, attacks were most likely to involve individuals or small groups with rudimentary weapons, often acting with little or no warning or planning, Burgess said.

He also cited a "resurgence" in the involvement of minors, with one recent perpetrator aged just 14.

Prime Minister Anthony Albanese said the government was working with social media companies to remove extreme and violent content and to trial age-verification technology.

The United States and Britain were also grappling with the rise of extreme ideologies, Albanese said.

"Governments around the world are concerned about youth radicalisation, online radicalisation, and the rise of new mixed ideologies," he said.

 -AFP