HE vanished from Darwin to help Kurdish fighters against Islamic State (IS) militants in Syria. Now politico Matthew Gardiner has been caught at Darwin airport.

Mr Gardiner was stopped by Customs officials early on Sunday morning.

He has been released without charge after being intercepted by Australian Federal Police.

The 43-year-old was the NT Labor Party President and boss of United Voice Union when he left Darwin in January, according to NT News.

In a statement to the NT News the AFP said it could confirm that it “spoke to a Darwin man today following his return to Australia”.

“Enquiries relating to his activities while overseas are ongoing and as such it is not appropriate to comment further at this time,” the statement said.

The AFP would not confirm if it was holding Mr Gardiner or if he had been released.

At lunchtime on Sunday there was a woman at the Gardiner family home who declined to offer comment when asked by an NT News reporter if Mr Gardiner was home.

The 43-year-old was the NT Labor Party President and boss of United Voice Union when he left Darwin in January.

The Sunday Territorian reported Australian officials believed the former army medic wanted to return to Australia and see his three young children.

But he risks being charged with an offence if he is found to have fought alongside the Kurdish resistance.

While Australia has transported shipments of firearms on RAAF planes to help the Kurds battle Islamic State, it remains illegal for Australians to fight in foreign conflicts.

Penalties can include lengthy jail terms.

The Australian Federal Police have previously confirmed they are investigating Mr Gardiner’s disappearance.

A spokesman said last night that the investigation was “ongoing’’ and they would not comment on whether Mr Gardiner was trying to negotiate his way home.

His wife Andrea Moriarty declined to comment Saturday on whether her husband had indicated he wanted to come home.

“I’ve got nothing to add to that. Have a lovely Easter,’’ she said.

After joining the Kurdish resistance to Islamic State in January, Mr Gardiner is believed to have contacted his wife just over a month ago to reassure he was still alive.

His texts followed the death of another Australian, Ashley Kent, 28, who was killed fighting against IS with the Kurds in northern Syria.

The Lions of Rojava website, which is a recruitment tool for foreign fighters wishing to join the Kurds has previously claimed Mr Gardiner had joined the national army of Syrian Kurdistan known as the YPG.

It is not known what his mission was but given his military background he may have been working as a medic. The website now prominently carries images of the Australian man killed in the conflict describing him as “hero’’ and urging other foreigners to join the People’s Protection Units in Syria, “send terrorists to hell and save humanity.’’

While authorities would not want to treat Mr Gardiner the same as returning foreign fighter for Islamic state, if he is found to have fought with the Kurds against IS has risked breaking Australian laws. Around 90 Australians are believed to have travelled to the Middle East in recent years as foreign fighters.

In January, Labor leader Bill Shorten said the union leader had made “a mistake’’ however well intentioned he was in trying to fight Islamic State.

“Whatever this guys motivations, he’s not going to solve anything by going over there,’’ Mr Shorten said.

“His family will be, I think, going through quite a bit of shock and confusion, so I don’t know what’s triggered this event but he needs to come home.’’