The Federal Government says a former Australian soldier has been killed fighting with rebels in Syria.

It says Caner Temel, from Auburn in Sydney's west, spent 17 months in the Army before going absent without leave in September 2010.

The ABC reported in January that Temel was shot in the head by a rebel sniper after a long siege on the outskirts of the Syrian town of Sareqeb, south of Aleppo.

The Government said the 22-year-old had served as a sapper based in Brisbane. It said he would have been discharged from the Army after being absent for 28 days.

Assistant Defence Minister Stuart Robert says the Defence Department is still working through issues of when Temel left Australia.

But the ABC understands that between June and August last year, Temel was recruited to fight the Syrian government for an Al Qaeda-affiliated militant group.

Mr Robert said Temel was working in a construction squadron at the time he went AWOL and had received basic arms and explosives training.

"All of our engineers will do a limited amount of explosives works in terms of clearing obstacles and that type of basic engineer work," he told AM.

The vast majority of foreign fighters who travel to Syria have no combat or military experience, making any military training in a recruit an asset to the rebel groups.

In January, it was reported that a Dutch soldier of Turkish origin who was disgusted by the West's failure to halt the killing in Syria had quit the army and travelled to the battle zone, where he was training rebels.

Last year, a former US soldier who fought with Syrian rebels, Eric Harroun, served a brief stint in an American prison after pleading guilty to minor charges involving conspiracy to transfer defence articles and services.

Sorry, this video has expired Stuart Robert discusses reports former Aust soldier killed in Syria ( AM's Chris Uhlmann )

Temel was reportedly recruited into the Islamic State of Iraq and the Levant (ISIS), which is listed as a terrorist group by Australia.

A number of Australians have been killed in Syria while supplying aid or fighting for factions within the rebel movement.

Temel's death in January came days after the killing of Sydney man Yusuf Ali and his young wife Amira near Aleppo.

The circumstances in which the couple died are still unclear, but it was reported they were also killed during fighting between rebel factions.

Roger Abbas, 23, a well-known kickboxer from Melbourne, reportedly went to Syria to do aid work, became involved with the Jabhat al-Nusra group, and was killed in October 2012.

Another Melbourne man, Yusuf Toprakkaya, was shot dead by a sniper while fighting for a rebel group in December 2012.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Listen Duration: 4 minutes 13 seconds 4 m 13 s Listen: Tim Palmer offers a glimpse into life under ISIS Download 1.9 MB

Sydney preacher Mustafa al-Majzoub was killed by a rocket while doing what his family said was humanitarian work in Syria in August 2012.

And a Brisbane man was suspected of being the first Australian suicide bomber after blowing up himself and a number of Syrian soldiers at a checkpoint last September.

It is believed there are dozens more Australians fighting in Syria, and that some have reached senior positions in extremist Islamic groups.

ASIO has also confiscated the passports of some Australians to stop them travelling to Syria and the wider region.

In December, Sydney man Hamdi Al Qudsi was arrested and charged with assisting people travelling to Syria to fight in the long-running conflict.

He faces seven charges under the Crimes Act relating to foreign incursions and recruitments.

Al Qudsi is accused of helping Yusuf Ali enter Syria "with the intent to engage in a hostile activity, in particular engaging in armed hostilities" between June and August last year.

Do you know more? Email investigations@abc.net.au