Counter-terrorism agents are closely monitoring about 40 foreign fighters already returned from battlefields in Syria and Iraq.
Australian Security and Intelligence Organisation director Duncan Lewis has confirmed at least 45 Australians have been killed in the conflicts in Syria and Iraq, with the number possibly as high as 49.
"Untrained and naive young Australians are being drawn into the conflict and finding themselves in what I would describe as highly expendable, highly dangerous positions of low importance amid the ISIL effort," Mr Lewis said on Tuesday.
Mr Lewis, appearing before a Senate committee in Canberra, said terrorism remained "the most obvious and most immediate challenge" for his organisation.
In his first appearance before the Legal and Constitutional Affairs Committee since May last year, Mr Lewis also confirmed about 40 Australians had now returned from battlefields in Syria and Iraq.
The majority had been involved in the earlier phase of the Syrian civil war, prior to advent of ISIL, also known as Islamic State, but remain under the close watch of authorities.
"Having concert with other Australian agencies we are working to identify the issues each of these individuals who have returned might present," Mr Lewis said.
"We're actively working to ensure that they're managed effectively and according to our law."
While there were 110 Australians fighting or engaged with terrorist groups in Syria and Iraq - a minor decrease since Mr Lewis last appeared before the committee last May - there had not been "an overall decrease in interest shown by individuals".
"The conflict in Syria and Iraq continues to resonate here in Australia," Mr Lewis said.
"There remains a small number of Australians that are influenced by the twisted rhetoric espoused by groups such as ISIL."
About 190 people in Australia continued to actively support ISIL, via fundraising or seeking to join the conflict.
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