Intelligence "chatter" has revealed that militants plan to attack Australian politicians and government buildings, the prime minister said on Friday, a day after hundreds of police carried out a sweeping counter-terrorism operation.
Prime Minister Tony Abbott said he had ordered security boosted at Parliament House in Canberra, amid mounting concerns over the possibility of attacks by Australians radicalised in Iraq or Syria.
More than 800 police were involved in the security operation in Sydney and Brisbane on Thursday, which authorities said had thwarted a plot by militants linked to the Islamic State group to behead a random member of the public.
"There are close links between Australians fighting with ISIL in Syria and Iraq, and networks of support back here in Australia," Abbott told reporters, referring to the group otherwise known as Islamic State that has seized large stretches of territory in Syria and Iraq.
"The chatter involving Parliament House was chatter between Australians in Syria and Iraq and their supporters here in Australia."
"I'm not aware that specific individuals have been named as part of this chatter, but certainly government, government people and Parliament have been referred to as part of this chatter," he said.
U.S. Secretary of State John Kerry on Thursday called the foiled plot an "extravaganza of brutality", and said it was evidence of the radical group's ability to attack targets outside the Middle East.
Australia is concerned over the number of its citizens believed to be fighting overseas with 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.
Abbott said at least 100 Australians are in the Middle East either fighting with or supporting Islamic State or other militant groups, a number that he said has been increasing in recent months.
At least 20 are believed to have returned to Australia and pose a security risk, and last week the national security agency for the first time raised its four-tier threat level to "high".
Highlighting the risk of homegrown militants returning from the Middle East, Abbott pledged on Sunday to send a 600-strong force as well as strike aircraft to join a U.S.-led coalition fighting Islamic State militants in Iraq.
REUTERS