An Australian man believed to be assisting in the ongoing war effort against Russian forces has been killed in Ukraine.

Michael O'Neill, 47, was believed to be in Ukraine helping the country with humanitarian aid when he was wounded and killed.

Mr O'Neill leaves behind three children and a family based mostly in Tasmania.

A Department of Foreign Affairs and Trade (DFAT) spokesperson says the family of Mr O'Neill has been contacted.

"DFAT is providing consular assistance to the family of an Australian killed in Ukraine. For privacy reasons we are unable to provide further information," the spokesperson said. 

Prime Minister Anthony Albanese commented on the Australian's death on Saturday.

"This is a tragedy and I want to give my condolences to the family of the person involved; the family has requested that their privacy be respected," he said.

A tribute to Mr O'Neill posted on Facebook says he was beloved as a "larrikin" family man who spent his time between the Philippines and Australia.

"He then assisted driving the wounded and injured from the front line. Unfortunately meeting a sad end, Mick had spent the last few years driving trucks in the mining industry and [spent] months in the Philippines with his children," the tribute post read.

A death notice published in Tasmanian newspaper the Hobart Mercury said Michael O'Neill left behind five brothers and sisters.

"We are all so proud of you, you did it your way" the newspaper obituary read.

A memorial service will be held at a local Tasmanian football club next month.

Russian troops are currently advancing through the east of Ukraine, gaining ground in Ukraine's Luhansk and Donetsk regions. 

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