Australia has raised its terror threat level to 'high' for the first ever time, citing the likelihood of terrorist attacks by Australian citizens radicalised in Iraq or Syria, despite stressing there was no knowledge of a specific attack plan.
Australia is concerned over the number of its citizens believed to be fighting overseas with Islamist militant groups, including a suicide bomber who killed three people in Baghdad in July and two men shown in images on social media holding the severed heads of Syrian soldiers.
David Irvine, the director general of the Australian Security Intelligence Organisation (ASIO), flagged the prospect of lifting the threat level on Tuesday, citing the growing risk posed by the returning fighters.
"Last night the director general of security raised the terror threat to high, consequently today the government is raising the public awareness level to high," Prime Minister Tony Abbott said in a news conference in Melbourne.
"I want to stress that this does not mean that a terror attack is imminent. We have no specific intelligence of particular plots. What we do have is intelligence that there are people with the intent and capability to mount attacks here in Australia."
Australia had been at the "medium" alert level since a four-tier system was introduced in 2003. A "high" alert level is used when officials believe an attack is likely, while a "severe" level means they believe an attack is imminent or has occurred.
Australian police on Wednesday arrested two men suspected of helping Australian citizens fight alongside militants in Syria on terrorism-related charges.
Up to 160 Australians have either been involved in fighting there or actively supported it, officials say, and at least 20 have returned to Australia after fighting in the Middle East and pose a national security risk.