Mike Burgess, director of the Australian Security Intelligence Organisation, said there was no indication an attack was imminent, but the risk of violence was increasing over the next 12 months.

"Australia's security environment is deteriorating, becoming more unstable and unpredictable... Politically motivated violence now, along with espionage and foreign interference, is our primary security concern," he said.

Burgess said more Australians were becoming radicalised and were increasingly willing to use violence to achieve their goals. “Individuals are embracing anti-government ideologies, conspiracy theories and a range of grievances. Some are combining multiple beliefs to create new hybrid ideologies,” he said.

Australian Prime Minister Anthony Albanese said he had raised the country's threat level on the advice of security agencies. "The advice we've received is that more and more Australians are embracing more and more extreme ideologies and we have a responsibility to be vigilant," he told a news conference.

Burgess said extremist ideologies have been on the rise during the COVID-19 pandemic and more recently during the Israel-Hamas conflict. “An escalation of conflict in the Middle East, particularly in southern Lebanon, will only add to tensions, exacerbate the situation and potentially increase grievances,” he warned.

In the past four months, eight incidents were believed to be linked or potentially linked to terrorism, he said. In one high-profile attack in April, a 16-year-old boy allegedly stabbed an Assyrian Christian bishop during a live-streamed church service in Sydney.

The head of the intelligence agency said social media and encrypted apps were making threats “harder to predict and identify”. He said the internet and social media were “a major platform for extremism and the use of encryption by all of our subjects”.

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

Prime Minister Albanese said the Australian Government is working with social media companies to remove extremist and violent content and trial age verification technology.

Mr Albanese said the US and the UK were also grappling with the rise of extremist ideologies. “Countries around the world are concerned about youth radicalisation, online radicalisation and the rise of new hybrid ideologies,” he warned.

Hoang Anh (according to CNA, AP)