The Australian Federal Police (AFP) has issued an arrest warrant for Queensland teenager Oliver Bridgeman, who says he has been in Syria doing aid work since May 2015.

Two AFP officers attended the Bridgeman family home in Toowoomba on Wednesday to inform his parents about the warrant.

The AFP confirmed it had obtained a warrant relating to "incursions into foreign countries with the intention of engaging in hostile activities". The alleged offence carries a potential jail term of up to life imprisonment.

Last month the Department of Foreign Affairs and Trade (DFAT) cancelled Mr Bridgeman's passport, just as his parents were finalising plans to bring him back to Australia via Singapore.

The ABC has learned the Bridgemans and their lawyer, Alex Jones, had alerted AFP officers to their plan in early February and had offered to bring Mr Bridgeman in for questioning once he was back in Australia.

Mr Jones from Bosscher Lawyers told the ABC Mr Bridgeman's parents were distraught.

"In their minds, it's just another example that they'd been lied to for the last 12 months after giving so much co-operation," he said.

Bosscher Lawyers issued a statement describing the Government's intervention as "a political stunt".

"It seems the government is doing everything possible to ensure Mr Bridgeman remains stranded in Syria," the firm said.

"Without government intervention, it is highly likely he would already be home. Mr Bridgeman had already indicated a willingness to cooperate with authorities."

Assessment detailed no evidence of dealing with terrorists

The issuing of the warrant means AFP officers have additional powers to intercept Mr Bridgeman, 19, and he can be flagged internationally as a wanted person.

Mr Bridgeman risks committing offences against Australian law if he is caught travelling without valid documents. He could also face prosecution in foreign countries through which he travels.

The ABC has seen the security assessment sent to Mr Bridgeman that was used to justify the cancellation of his passport.

The recommendation that DFAT cancel the passport was signed by ASIO director-general Duncan Lewis on February 10 and was delivered to his parents on February 16.

The security assessment cites "open-source reporting" and "domestic liaison reporting by (Queensland police)".

"On the 15th and 16th of May 2015 Australian national print media reported Mr Bridgeman had travelled to Syria without the knowledge of his parents and was suspected by the AFP of having joined a proscribed terrorist organisation," the document stated.

The assessment referred to Facebook posts by Mr Bridgeman describing his aid work and a TV appearance by Mr Bridgeman last year in which he was pictured doing aid work and saying he had built a "good relationship with different rebel factions" in order to move safely around Syria and avoid kidnap.

Dutton defends cancellation of passport

No terrorist group is named in the security assessment and no evidence is included of Mr Bridgeman having had dealings with any proscribed group.

"ASIO assesses that Mr Bridgeman travelled to Syria for the purpose of engaging in PMV [politically motivated violence]," the document stated.

"Mr Bridgeman likely remains ideologically supportive of PMV and would be likely to engage in conduct that might prejudice the security of Australia.

"ASIO assesses that, based on Mr Bridgeman's travel to Syria to engage in PMV, that if Mr Bridgeman continues to hold an Australian travel document he would be likely to engage in conduct that might prejudice the security of Australia."

The Bridgeman's lawyers this week filed an appeal against the passport cancellation in the Administrative and Appeals Tribunal on behalf of Mr Bridgeman.

The ABC understands that in such cases it is open to security services to provide a judge with further evidence that is not disclosed to the defendant or their lawyers.

Immigration Minister Peter Dutton has defended the decision to cancel Mr Bridgeman's passport, saying: "People who go off into conflict zones — even if they're well intentioned — ultimately can cause significant grief and stress for their own families".

"This is something people should contemplate before they go — not when they're in the middle of a conflict zone."