Prime Minister Anthony Albanese said he had raised the country's threat level following advice from security services, but said there was no imminent threat of an attack.

"The advice that we have received is that more Australians are embracing a more diverse range of extreme ideologies and it is our responsibility to be vigilant," he told a news conference. 

Australia lowered the threat level to "possible" in 2022, following eight years at "probable". 

Mike Burgess, director general of the Australian Security Intelligence Organisation, the country's main intelligence agency, said tensions in the Middle East, including a conflict between Israel and Hamas that began on Oct. 7, were a contributing factor to raising the threat level.

"The conflict has fuelled grievances, promoted protests, undermined social cohesion and elevated intolerance," he said. 

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. 

Australia has seen several violent attacks in recent months, some of which have been designated as motivated by extremism. 

In April Australian police said a knife attack on an Assyrian church bishop and some of his followers in Sydney was a terrorist act motivated by suspected religious extremism.