Australian police said on Sunday they were investigating a former trade union official and member of the Australian Labor Party following reports that he has travelled to Syria to join the fight against Islamic State militants.
The Australian Broadcasting Corp. reported that Matthew Gardiner, 43, has left for Syria where he intends to join Kurdish fighters battling against the Islamists.
The Australian Federal Police confirmed to Reuters that Gardiner is under investigation but declined to comment further.
A spokeswoman for United Voice, a labour union that represents miners, emergency and hospitality workers, said Gardiner had recently resigned from his position as secretary of its Northern Territory branch.
Gardiner is also president of the Northern Territory branch of the Australian Labor Party, and its secretary Kent Rowe told the ABC that he was on leave and hadn't been heard from in weeks.
The Australian government introduced sweeping security reforms last year over concern at the number of its citizens heading to Iraq and Syria to fight. About 90 Australian citizens are estimated to be involved in the conflict.
It is illegal for Australian citizens to support any armed group in Syria and fighters face life in prison upon return.
"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," a spokesman for the Attorney-General's department said in a statement.