The Australian Border Force (ABF) has intercepted a total of 336 "suspicious travellers" at the country's international airports since 2014.
The ABF revealed on Thursday that its counter-terrorism unit (CTU) officers had stopped the travellers from boarding international flights up until June this year, Xinhua news agency reported.
The ABF's 2014-15 annual report showed that customs officers conducted more than 133,000 "real-time assessments" on more than 9,200 patrols.
It said that officers stopped a "number of people of national security concern", which included a high number of "minors from travelling to conflict areas in Syria and Iraq".
Since the conflict involving Islamic State (IS) in the Middle East escalated, CTU officers have been able to carry firearms and select travellers for random screenings, following a government decision to crack down on those leaving for the conflict zones.
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"Upon examination of persons of concern, the CTU teams have found evidence of significant movements or attempted movements of large sums of cash, and images and material of an extremist nature," the report said.
"Some cases have resulted in the imposition of infringement notices, while others are the subject of ongoing investigations."
It was also revealed that the government cancelled the passports of 67 suspect travellers - up from 45 in the previous year - in 2014-15.
In the past three months, more than 20 passports have been cancelled by the immigration department.
