Kurdish peshmerga fighters in Iraq (file)
Kurdish peshmerga fighters in Iraq (file)Reuters

A former unionist and Australian political figure has been detained at Darwin Airport after returning from the Middle East where he is believed to have been fighting against the Islamic State group, a report said Sunday.

The Australian Broadcasting Corporation said it understood that Matthew Gardiner was stopped by customs officials early Sunday after flying in to the northern Australian city via Sweden and Singapore.

The Australian Federal Police confirmed that its officers "spoke to a Darwin man today following his return to Australia", but did not name the

"Enquiries relating to his activities while overseas are ongoing and as such it is not appropriate to comment further at this time," a police spokesman said.

Gardiner, a former trade unionist and ex-president of the Northern Territory branch of the opposition Labor Party, reportedly left Australia
early this year to join a Kurdish militia fighting ISIS.

Australia is involved in the US-led coalition against ISIS in Iraq and last year passed a law criminalizing travel to terror hotspots, in an measure designed to stop jihadists from going to Iraq and Syria to fight.

But fighting for either side in the conflict in Syria and Iraq is understood to be punishable on return to Australia.

"Australians risk prosecution under Australian law if they fight in other countries," the Department of Foreign Affairs says on its travel warning for Iraq.

Gardiner reportedly served as an Australian Army combat engineer in Somalia in the 1990s, but has since married and has three children.

He was removed as the Northern Territory chief of the Labor Party and suspended from the organization after the news he had traveled to the Middle East emerged, the ABC said.

Federal Labor leader Bill Shorten expressed relief Sunday that Gardiner was "back home safe and sound." 

"But I'm concerned anyone thinks they should be getting involved in these foreign conflicts, no matter what their intentions," he said, the ABC reported.

The Australian government has increasingly been sounding the alarm about radicalized citizens, with about 90 thought to be fighting with the Islamic State group in Iraq and Syria.

AFP contributed to this report