Kurdish fighters are increasingly using Facebook as a recruitment tool to attract Westerners to fight against Islamic State (IS), international experts warn.

The ABC revealed former Labor Party NT president Matthew Gardiner, who is also a former soldier, had left Australia earlier this month intending on joining Kurdish fighters in Syria.

Mr Gardiner befriended a woman on Facebook named Kader Kadandir, who has links with various Kurdish rebel groups, including a Facebook page called the Lions of Rojava, which has more than 36,000 likes.

The group is thought to have attracted former American soldier Jordan Matson, and former British soldiers Jamie Read and James Hughes. The group also claimed it was contacted by foreign fighters from other nations.

"I've had ex-military come from Eastern Europe, Western Europe, Canada, the United States, Australia," Mr Matson, a recruiter for Kurdish fighters, told CNN in an interview last year.

He said IS had threatened many countries, and veterans of those nations did not want to sit by and let that happen.

Experts said Kurdish groups recruiting non-ethnic Kurds changed the dynamic of the conflict.

"I think that the situation is turning into a global jihiadi and counter-jihiadi struggle," Professor Amin Saikal from the Australian National University said.

"We know a great deal about Islamic State recruitment processes in the West, but certainly not about the Kurdish recruitment circles.

"But it's very clear through this Lions of Rajova [page] that Kurds have become very active."

Can Australians legally fight with Kurdish groups?

Govt's view on Australians wanting to fight with Kurds It is possible to join the legitimate armed forces of a government of a foreign country. However, Australia's sanctions regime makes it an offence to fight for any side in Syria.

It is possible to join the legitimate armed forces of a government of a foreign country. However, Australia's sanctions regime makes it an offence to fight for any side in Syria. The Kurds are not recognised as the legitimate armed force of Iraq - any Australian fighting for the Kurds in Iraq may be committing an offence.

The Kurds are not recognised as the legitimate armed force of Iraq - any Australian fighting for the Kurds in Iraq may be committing an offence. The Government's strong message is clear – do not participate in the fighting as it only contributes to the suffering and puts you and others in mortal danger. Instead, there are legitimate ways to help, such as by contributing money to UN organisations.

The Government's strong message is clear – do not participate in the fighting as it only contributes to the suffering and puts you and others in mortal danger. Instead, there are legitimate ways to help, such as by contributing money to UN organisations. Approximately 90 Australians are currently engaged in war fighting in Syria and in Northern Iraq. Over 100 people in Australia are supporting foreign fighters and terrorist organisations through activities such as funding and facilitation. Source: Australian Attorney-General's Department

The Australian Government is aware of about 90 Australians who have travelled to the Middle East to fight with Islamic State or similar terrorist groups.

However, it is unknown how many have gone to fight with Kurdish groups, which have been backed by air strikes from Western allies including Australia.

Upon their return to their homeland in England after fighting with the Kurds, Mr Read and Mr Hughes were not charged with any offence, and even conducted media interviews about their experiences.

A statement from the Attorney-General's Department said while it was possible to join legitimate armed forces of a foreign country, it was illegal for Australians to fight on any side in Syria.

The statement said there were legitimate ways to help in the conflict, such as by contributing money to UN organisations.

Professor Saikal said anyone who joined the Peshmerga, a Kurdish group fighting Islamic State in northern Iraq, should be very careful.

"The Peshmerga has its own agenda and of course they have sought extensive autonomy in northern Iraq and would like to create an independent Kurdistan," said Professor Saikal.

Will Matthew Gardiner face charges?

NT Labor president and former United Voice NT secretary Matthew Gardiner has left Australia to fight against Islamic State. ( ABC News )

What will happen to Mr Gardiner is not clear, but an Australian Federal Police investigation into his activities is underway.

The best lead on where he has gone is linked to Ms Kadandir, whose politics are clear from her Facebook page.

She heaps praise on a range of Kurdish forces who are battling IS in Syria, and posts photographs and videos of battles.

Who are the groups? PKK: Kurdistan Workers' Party (listed terrorist organisation in Australia) that has had a history of armed struggle against Turkey.

Kurdistan Workers' Party (listed terrorist organisation in Australia) that has had a history of armed struggle against Turkey. YPG/YPJ: Known also as the Lions of Rojava or the People's Defence units. They describe themselves as the army of Syrian Kurdistan. The groups have been linked by some to the PKK but the Australian government does not specifically list YPG or YPJ as a terrorist group.

Known also as the Lions of Rojava or the People's Defence units. They describe themselves as the army of Syrian Kurdistan. The groups have been linked by some to the PKK but the Australian government does not specifically list YPG or YPJ as a terrorist group. HPG: The Hezan Parastina Gel is seen by the Australian Government as part of the PKK. Sometimes the HPG is referred to as the armed wing of the PKK.

The Hezan Parastina Gel is seen by the Australian Government as part of the PKK. Sometimes the HPG is referred to as the armed wing of the PKK. Islamic State: An Islamist group known sometimes as ISIS or DAESH and listed as a terrorist organisation in Australia. It proclaims itself to be a caliphate with authority over Muslims.

As well as the Lions of Rojava, Ms Kadandir promotes a group known as the YPG, otherwise known as the Kurdish People's Protection Units, and in a recent post on her Facebook page, Ms Kadandir indicates the group is part of the Kurdistan Workers Party (PKK).

"Long live Humanity fighters PKK (YPG & YPJ & HPG and YJA-STAR)," she wrote.

The link between the PKK and the YPG is important, as Australia includes the PKK as a listed terrorist organisation and also lists the HPG (Hean Parastina Gel) as a pseudonym for the PKK.

Anyone found guilty in Australia of associating with a terrorist organisation can face up to three years in jail, or 10 years' jail if found to be a member of the group.

That penalty can jump to 25 years' imprisonment if the person recruits for the group, receives training from them, acquires funds for them or otherwise supports them.

Professor Greg Barton is the director of the Global Terrorism Research Centre at Monash University and said Mr Gardiner would be breaking the law.

"It's true that fighting with Kurdish fighters against Islamic State, that's generally seen as being on the side of good, but it's still breaking Australian law," Professor Barton said.

"The law may be a blunt instrument but it has to be that way because stopping foreign fighters going in general is an urgent necessity."

Why would the Kurds want Mr Gardiner in their ranks?

As well as being an influential politician in the Northern Territory, where he was head of the local branch of the Labor Party, Mr Gardiner has been trained in the Army as a combat engineer.

Combat engineers are specialists in activities including minefield clearance, field defence systems and water purification among other things.

Mr Gardiner also became an engineer surveyor when deployed by Australia to a conflict in Somalia in 1993.

Engineer surveyors are involved in construction of airfields, bridges, railways and roads, and are trained in infantry fighting.

After leaving the Defence Force, Mr Gardiner studied nursing and after becoming a registered nurse worked in the emergency department and operating theatre of the Royal Darwin Hospital.

The ABC has attempted to contact Mr Gardiner but he has not responded to messages.