Authorities could have stopped a Sydney teen who left home suddenly and believed to be en route to join the fighting in conflict-torn Iraq, a lawyer for the boy's family says.
But the Attorney-General's Department says it was unaware the teenager, from Sydney's Western Suburbs, was planning on travelling.
Abdullah Elmir, 17, went missing from his home at Bankstown in Sydney more than a week ago and called his mother to say he was in Turkey about to "cross the border".
The lawyer representing the family, Zali Burrows, said his mother understood that to mean Abdullah was heading to Iraq.
She wants to know how the teenager and another 16-year-old boy he was travelling with were not stopped on their way.
"The family went to the media today as a plea to the government to bring their boy back," Ms Burrows said.
"We know they have the intelligence to pinpoint him.
"The concern is that he's being used as a tracking device to gather further intelligence, to see where he's actually going to go."
The family was expected to hold a press conference in Bankstown on Sunday, but cancelled soon before it was due to start.
Abdullah told his family he was going fishing on Friday June 20, but instead is understood to have left the country with a 16-year-old companion.
Ms Burrows said the family have never met the other boy.
"Abdullah said he'd gone fishing, but then his mother received the phone call. As you can imagine that'd loor anyone," Ms Burrows said.
The pair are believed to have taken an indirect route, travelling from Sydney to Perth and then Malaysia and Thailand before finally reaching Turkey.
The Australian Security and Intelligence Organisation (ASIO) said last week it is monitoring 150 citizens in Australia and overseas who have suspected links to "violent extremist groups".
"Young Australians are going overseas and getting themselves killed in foreign conflicts," director-general David Irvine told a Senate estimates hearing on Thursday.
In a statement to AAP, the Attorney-General's Department said no government agency, including the Australian Federal Police, was aware of Abdullah's travel plans.
The department said it was of particular concern that youths were putting themselves at risk of kidnapping, serious injury or death, and of potentially taking part in the conflicts in taking place in places such as Syria and Iraq.
"However, individuals make, and are responsible for, their own travel decisions," the statement said.
"The government only seeks to prevent a person from travelling overseas if they are believed to be seeking to engage in activities prejudicial to national security.
"Parents and the broader community share the responsibility to partner with the government in educating their children about the risks associated with travelling to Syria and the region and ensuring they do not put themselves or others in danger."
Under Australian law it is not illegal to travel to Syria or Iraq.
However it is illegal to take part in or provide material support for either side of the armed conflict in Syria.