The former president of the Northern Territory Labor party, believed to have been overseas fighting Islamic State, has been released without charge after being detained upon return to Australia.
Matthew Gardiner reportedly left Australia earlier this year to join Kurdish forces and was stopped by authorities when he arrived at Darwin airport early on Sunday.
He has not been charged, an AFP spokesman said.
“Enquiries relating to his activities while overseas are ongoing and as such it is not appropriate to comment further at this time,” he said.
Mr Gardiner, 43, served as an Australian Army combat engineer in Somalia in the early 1990s, the ABC reports.
Australians fighting illegally overseas can be jailed for life, Attorney-General George Brandis’s office has previously warned.
Senator Brandis declined to comment on Sunday, with a spokesman saying it was inappropriate as the matter was under investigation.
Federal Labor leader Bill Shorten told the ABC he was relieved Mr Gardiner was home but concerned he had been fighting overseas.
A spokesperson for Attorney-General has previously said it was illegal for Australian citizens to support any armed group in Syria, even though the Australian Defence Force and Kurdish rebels may share a common enemy.
“It is illegal to fight in Syria for either side of the conflict,” the spokesperson said.
“If you fight illegally in overseas conflicts, you face up to life in prison upon your return to Australia.
“We know there are some Australians who think they’ve made the right choice in becoming involved in overseas conflicts, but that choice only adds to the suffering in Syria and Iraq and it’s putting those Australians and others in mortal danger.”
The Australian government does not recognise the Kurds with whom Mr Gardiner allegedly fought as a legitimate armed force.