An Australian soldier volunteering as a combat medic in war-torn Ukraine has been killed in action. 

'Mozzie the Aussie', a respected former Townsville soldier, had been serving with the Ukrainian International Legion's Med Team Alpha.

A close family member confirmed Mozzie’s death to The Australian, saying it was verified by soldiers who were with him when he was killed on Friday. 

After leaving the Australian Army, Mozzie travelled to Ukraine, where he served as a combat medic and support specialist with Med Team Alpha and the 1st Foreign Legion Squadron.

A social media page dedicated to fallen Australian Defence Force personnel included a tribute from one of Mozzie’s close friends on the frontline. 

He described Mozzie as 'the bravest soldier I have ever known'.

'As a combat medic he pulled countless people back from the edge, and he also took out multiple enemies,' the soldier wrote.

'I was there for most of what he did in this war. After everything we had already been through, very few still wanted to keep fighting. Mozzie did.'

The unnamed soldier claimed Mozzie killed six enemy troops after they opened fire and killed his team leader and best friend.

He said Mozzie desperately tried to keep his team leader alive until a vehicle arrived to evacuate him.

The Department of Foreign Affairs and Trade has not officially confirmed Mozzie’s death but is understood to be making inquiries with Ukrainian authorities. 

Shadow minister for defence personnel Phil Thompson paid tribute to the fallen soldier on social media, calling him a mate who earned the respect of those who served with him. 

'Mozzie proudly served his country as a member of the Townsville-based 1st Battalion, Royal Australian Regiment, including deployments on RCB and to Papua New Guinea,' he wrote.

'He was a valued member of the Battalion's Heavy Weapons Platoon, affectionately known as the 'Fatboys', and earned the respect of all who served alongside him.

'Through his courage, skill and selfless commitment to others, Mozzie saved countless lives on the battlefield.

'He was the kind of bloke who never hesitated to put others before himself.

'He was a good man, a great soldier, and someone his mates could always rely on when it mattered most.

'As Mozzie's mate and fellow veteran, I know there are many in our military and veteran community who will feel this deeply ... stand down, brother. Your duty is done.'

While in Ukraine, Mozzie amassed thousands of Instagram followers, sharing his experiences as a frontline combatant. 

According to Ukraine's military ombudsman, about 16,000 foreign volunteers from more than 70 countries are serving alongside Ukrainian forces.

As many as 14 other Australians, including 26-year-old former ADF soldier Samuel Pedrazzini, have been killed fighting in Ukraine.

Former Melbourne schoolteacher Oscar Jenkins was sentenced by a Russian court last year to 13 years in prison after being captured while fighting for Ukraine.

The Australian government has repeatedly warned Australians against travelling to frontline areas of the war-torn country.