Up to 70 children of Australians have been exposed to extremist groups in the battlefields of Syria or Iraq, the country's security chief has revealed.
Duncan Lewis, director-general of the Australian Security Intelligence Organisation, said these children either travelled to the conflict zones with their Australian parents or were born there.
He told a Senate committee late on Tuesday night that ASIO is investigating around 190 people in Australia who are actively supporting groups like IS through recruiting, fundraising or wanting to join themselves.
That includes about 40 Australians who have returned from Syria or Iraq.
"The long-term impact of the returnees will be a security issue for this country's intelligence and law enforcement agencies for many years to come," he said.
Mr Lewis confirmed up to 68 Australians are believed to have been killed in the conflicts - 11 of them since May.
Around 110 people are still fighting or engaged with terrorist groups in Syria and Iraq.
"As ISIL's territory continues to contract, it's expected that many of those Australians who are supporting ISIL in Syria and Iraq will be killed or captured," he said, using another acronym for Islamic State.
Mr Lewis warned that action will be taken against anyone who returns to Australia after committing a terrorist attack for the sake of national security.
To date, ASIO has recommended the cancellation or refusal of over 190 passports of Australians linked to extremist groups.
More than 20 visas for non-Australians have also either been cancelled or refused.
"Let me be absolutely clear: the threat of terrorism in Australia is real and present in our community," Mr Lewis said.
"It required vigilance by both the Australian community and abroad, and governments of all levels to continue to combat it."
The intelligence head also highlighted the existential, insidious and strategic threats posed by espionage.
While he couldn't provide specific details, he said the threat was ongoing and pervasive.
"It's more significant than many in our community would realise."
ASIO, among other things, provides advice to the government on security threats that might be posed by the lease or purchase of Australian assets of strategic or national significance.
