Australia’s counter-terrorism chief has warned of a rise in youth radicalisation fuelled by online extremism, as he raised alarm about the spread of harmful rhetoric from foreign “propaganda machines” and social media platforms with no regard for content moderation.

Experts appearing before the Royal Commission on Antisemitism and Social Cohesion on Tuesday warned “nihilistic violent extremism” was pushing young people to pursue violence for its own sake as government responses to radicalisation came under the microscope.

Brendan Dowling, who was named counter-terrorism coordinator at the Department of Home Affairs in May, sounded the alarm on nihilistic extremism as an emerging driver of terror that glorifies violence and is absent of a structured ideology.

It differed from previous iterations of terrorism by promoting violence itself, rather than considering it a method to advance an ideology or cause, Dowling said.

The trend has intensified the work of tackling mixed and unclear ideologies through counter-terror circles, as new trends of radical behaviour flourish in online environments.

“There is a lot of evolution, a lot of fluidity, and it is something that I think even long-standing experts would appreciate that you’re never on top of,” he told the commission. “There’s always a continued process of learning.”

Youth Justice NSW specialist support unit senior manager Steve Barracosa told the hearing extremist themes can intersect in “quite incoherent ways”.

“Nihilistic violent extremism has become a bit of a catch-cry for misanthropic, violent, gore, objectionable spaces online where meshed ideas are mixing together,” he said.

Barracosa said youth extremism programs have expanded since 2022 as the problem evolved beyond religious and ideologically fuelled radicalisation with the emergence of “a really broad and convoluted right-wing extremism landscape with many different themes and ideas”.

“We’ve observed antisemitic narratives, ideas, and in some cases ideologies across different pockets of the extremism landscape, particularly religious and right-wing extremism,” he said.

But antisemitism was seldom the core defining feature or most prominent theme of a radicalised young person’s extreme beliefs.

“We’re living in a rather complex, divisive, provocative, and emotive socio-political climate, which I think must be incredibly difficult for younger, increasingly vulnerable cohorts to navigate,” Barracosa said.

He warned young people are more susceptible to “short, sharp, very intense radicalisation trajectories” that can occur online.

Naveed Akram and father Sajid Akram are accused of conducting the Bondi Beach massacre in December after being radicalised by IS propaganda. Their car was adorned with an IS flag, and they allegedly recorded a video manifesto containing the terror group’s iconography.

The younger Akram survived and is awaiting trial on murder and terrorism charges. Sajid was shot and killed during the attack.

Dowling flagged a “disturbing” uptick in young Australians being swept up by online extremist material promoting neo-Nazi, white supremacist, Jihadi and anti-government movements, saying that the spread of harmful rhetoric online meant “effectively anyone” could engage with radical ideology.

“Your average Australian … might have a sort of stereotype in their head of what an extremist or a terrorist looks like, or how they behave ... we’re seeing such [a] greater variance in types of people engaging with radical ideas,” he told the commission.

Australia’s counter-terror authorities found that online material, seeking to legitimise ideological grievances and justify acts of violence, is “nearly always” driving radicalisation, according to Dowling.

“In nearly all cases there is an online dimension where [there is] access to violent extremist material online, access to a community of like-minded people, who foment that sense of grievance and anger,” he said.

Dowling pointed to hateful rhetoric spread by voice on gaming platforms during live sessions. He also took aim at social media operators, accusing them of not doing “as much as they can” to stop violent content spreading, and foreign actors “trying to fuel that sense of grievance”.

“The Russian government globally operates propaganda machines, bot campaigns that try to identify divisive topics, extremist topics, and fuel those because they see that as part of their geostrategic agenda,” said Dowling, who also singled out Iran and its proxies “potentially” engaging in similar work.

“When you see material that is promoted and available online because of its level of views or its virality that is not necessarily natural or organic … that is, I think, an increasing area of concern for us.”

Corrective Services NSW assistant commissioner Danielle Matsuo told the hearing of the importance of early intervention in combating extremism.

“By the time people come to us, they often have very entrenched views and beliefs,” he said.

Forming new habits, behaviours and “new ways of navigating the world” is central to custodial de-radicalisation programs, Matsuo said.

Efforts to disengage young people from radical ideas depend heavily on their own willingness, family engagement and care provision, but Barracosa said intense intervention needs to be sustained to be successful.

“Short gains are positive, but the maintenance of those gains requires service providers to remain involved with any given young person over a prolonged period,” Barracosa said.