As Australians face the prospect of homegrown terrorism, authorities are investigating whether extremists have pushed their ideology on students at a school in south west Sydney.
An insider has told 7News one former student may have already travelled to the Middle East to join Islamic State.
An anonymous source from East Hills Boys High school says teachers are fearful school boys have been targeted by radicals.
“We've had the federal police have been at that school, or the school has been under surveillance for the past 6 months to my knowledge,” the source told 7News.
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“There are a few students involved in, or possibly can be involved in, illegal activity.
“When I mean illegal activity, I mean part of cells or something like that, who [are] actively preaching, and preaching hate against people here in Australia.”
7News can confirm New South Wales and the Australian Federal Police investigated an incident in June when a pair of 14-year-old students refused to stand for the national anthem.
When questioned, it is understood the boys said they did not stand for the anthem because they "only stand for god", "do not respect this country" and because Australia "sends troops to Afghanistan to kill our men and rape our women".
In a statement, the New South Wales Education Department confirmed the incident had occurred and that "the school took appropriate follow-up action, including talking to with the students family".
Police identified one of the students as being involved in the 2012 Hyde Park riots, holding a sign inciting violence.
Muslim community leaders are at pains to point out these ideas do not belong to true Islam.
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“Our kids should rely on the teaching from respectable, reliable, well informed religious leaders,” Jamal Rifi said.
Despite this, police discovered that a close associate of Hamdi Al Qudsi was leading prayer sessions held at East Hills High.
Al Qudsi was charged in 2013 by Counter Terrorism police for providing "money and or goods in support of foreign hostile acts”.
Authorities worry Al Qudsi's associate is using the prayer groups to preach his extreme ideology.
“They are using the religion as a tool for political propaganda,” Mr Rifi said.
7News has learned that the school has now removed the religious advisor from his position, at the request of the police.
The Education Department clearly states that "Special Religious Education can only be delivered by authorised representatives”.
But our source claims this was clearly being breached.
“We've got prayers that are running Fridays and you know, we have outsiders walk into that school without signing on,” the source said.
“No one knows who they are, their credibility or anything like that.”
Terrorism expert Greg Barton believes the school did the right thing in calling Police.
“Three quarters of all the people being recruited as foreign fighters into extremist ideas are young men in their teenage years and in their 20s, that includes school students.”
One teenage student at East Hills High may have already left Australia to fight with terrorists.
“I know that there is a kid, allegedly Fayez Kanaan, I believe he has gone overseas and taken up arms… that student is definitely not at school,” the source told 7News.
“And, to my knowledge, I think that's why we've got the federal police investigating.”
A source has confirmed the AFP has been investigating the movements of a 17-year-old student who has travelled to Turkey.
7News cannot confirm what he did when he got there, or if he travelled to Iraq or Syria.
The student's social media account shows his bedroom wall adorned with the Islamic State flag and photos rejoicing the deaths of US soldiers.