Australian Security Intelligence Organisation

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.

Australian police on Tuesday said a brutal knife attack during a live-streamed church service was a religiously motivated "terrorist" act, as they urged calm from the angered local community.

Two people were stabbed when a 16-year-old suspect rushed the dais at an Assyrian Christian church in western Sydney late Monday, slashing wildly at the bishop who was giving a sermon.

Australians are becoming key players in the successful "social media wars" being waged from Iraq and Syria, increasingly acting as "English-language Islamic extremist propagandists", the country's spy chief has warned.