An Australian man who went to Syria to fight against Islamic State has challenged authorities to arrest him or leave him alone.

Key points: Ashley Dyball left Australia in 2015 to fight with a Kurdish militia against IS

Ashley Dyball left Australia in 2015 to fight with a Kurdish militia against IS On his return in December he was questioned by the AFP but not charged

On his return in December he was questioned by the AFP but not charged He is still under investigation

Ashley Dyball joined the Kurdish YPG militia in May 2015 and returned to Australia last December.

On his return the Australian Federal Police (AFP) questioned him for breaching foreign fighter laws.

His passport was confiscated and he has been under investigation ever since.

"If I'm the bad guy, then f***ing charge me," Mr Dyball challenged the AFP when he talked to 7.30.

"I don't care. I'll do my time."

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Mr Dyball believes the investigation into his activities shows a double standard in the Federal Government's position.

"You [the Government] say we can't fight for them [the YPG], but yet you fund them," he said.

"You'll air strike for them. You'll aid them. So how is it OK for you to aid them and I can't aid them?"

'This was something I felt had to be done'

Mr Dyball became interested in the conflict in Syria three years ago and became increasingly agitated by the atrocities he saw committed by Islamic State.

"The main drive for me to go over there was just to help the children and the people," he said.

"I was just sick of seeing women and children beheaded, raped, it just didn't sit well with me.

"I was never originally going over to fight or nothing like that. I was just going to go help in hospitals and shit like that.

"I probably thought about it for well over a year — never said a word to anyone, just did it in silence, nothing on your home computer or anything like that, burner phones, libraries, things like that."

Ashley Dyball (L) and Joe Ackerman (R) with mines they have cleared from Kurdish villages. ( Supplied: Ashley Dyball )

He knew that if he went he would be breaking the law.

"I did my research, I knew it was frowned upon to go," he said.

But he decided to go anyway.

"This was just something I felt had to be done," he said.

"We've had laws in the past that have been overthrown because they were wrong. Just because it's the law doesn't mean it's right."

'You're just shooting at them'

In May last year Mr Dyball told his parents he was going on a European holiday, and asked them to drop him off at the airport.

Instead, he travelled to Rojava in northern Syria, to join the YPG militia.

Within weeks he was on the front line near the Turkish border, clearing Kurdish towns and villages of IS militants.

Speaking about the operation for the first time, he confirmed he was involved in active combat against IS.

"You're just shooting at them, just to keep them contained as best as you can," he said.

"But from that distance, they've got houses, towers, water towers, little mud huts, so you just shoot it wherever you can see.

"If you can see a flash you can shoot at it. If you can see movement you can shoot at it. But you also have to be very wary, it could be a civilian."

Despite his lack of military training, Mr Dyball quickly felt comfortable in the war zone with his new Kurdish comrades.

"If you go out to that fight, you make one mistake, someone's dead. And you can't allow that to happen," he said.

"It's not a game over there. You cut that wrong wire, you're dead, someone else is dead.

"You step on one because you didn't look hard enough, you're dead, someone else is dead."

Two weeks later he was back at the front with an all-Kurdish unit.

It was the first time he saw the full brutality of Islamic State, when a teenaged comrade picked up a rigged box of chocolates, which exploded, ripping off his right arm.

The death of Reece Harding

Eventually Mr Dyball found his way onto the sabotage team, where he joined up with fellow Australian Reece Harding.

"We were mates, but we weren't the best of mates. But as time goes on you learn more about the people and that's when you start becoming really good mates," he said.

"[Reece] was one of those genuinely nice blokes. Just cool, calm, collected. And he did what needed to be done."

Ashley Dyball and Reece Harding in Syria. ( Supplied )

As part of the sabotage team their task was to remove mines and booby traps left behind by IS.

"They rig them to dead bodies, they rig them to weapons, even little civilian kids, they'll rig them to that," he said.

"So you'll go to a dead civilian kid, to move it or put cover over and put it somewhere safe, you'll pick that kid up and you'll blow him up — and you up.

"If you don't get every single one of them, one day you'll have a kid playing footy with his mates, kicking a soccer ball around, the next moment he's stepped on one and lost his leg.

"That happens a lot."

And it happened to Harding.

One day the two were asked to go with a Kurdish commander to get food and other supplies.

But at the last minute it was decided that only one should go and the other should stay behind.

Mr Dyball left for supplies.

That night Harding stepped on an improvised explosive device (IED), which killed him instantly and wounded five others.

When Mr Dyball got to the hospital he asked three Westerners where Harding was.

"That's when Joe told me, 'Reece is dead'," he said.

"I was like, you're f***ing joking, mate."

'No parent should have to answer that phone'

Michele and Keith Harding holding a framed photo of Reece. ( AAP: Dan Peled )

It was decided that Mr Dyball would call Harding's parents in Australia to break the bad news before the media found out.

He texted Keith and Michele Harding asking them to phone.

"I was like, 'sorry mate, sorry to tell you, Reece is dead'," he recalled.

Harding's father hung up and then called back.

"You could hear Michele crying in the background," Mr Dyball said.

"We spent about an hour just chatting to them, and it was probably the hardest thing I had to do over there.

"No parent should have to answer that phone to find out their child is dead."

No regrets about return to Australia

Despite these traumatic experiences, Mr Dyball was determined to stay in Syria and support the Kurdish cause.

"You can either sit down and have a sook, it's not going to bring your mates back, or you can keep going forward and let their memories live on in you and achieve what we all set out to do," he said.

In December he went to Europe for a short break. He was detained in Germany because, he says, he was on an Interpol watch list.

Faced with an ultimatum of fighting potential terrorism charges in Europe or returning to Australia, Mr Dyball opted to return home.

When he arrived at Melbourne airport, the AFP pulled him aside and questioned him about his time in Syria.

Ashley Dyball returned to Brisbane in December last year. ( AAP: Dan Peled )

While he remains under investigation for a potential breach of Australia's foreign fighter laws, he is yet to be charged with any offence.

And he says he has no regrets about going to Syria.

"I didn't really care what anyone thinks of me. I didn't do it for anyone's approval. It's not about that. It's about helping those people," he said.

"If no-one likes me for that, if people think it's the wrong decision, well, I don't give shit. It's my life, my decision, and I made it."

In a statement to 7.30, a spokesman for Attorney-General George Brandis said: "The Australian Government has, for a number of years, strongly and consistently discouraged Australians from travelling to conflict zones such as Syria and Iraq to participate in hostile activities.

"It is dangerous, it puts others' lives at risk, and it may constitute a criminal offence.

"Australian security and law enforcement agencies manage individuals of security concern on a case-by-case basis.

"These laws do not differentiate between various non-government militia groups involved in foreign conflicts."