The boy is the son of Australian jihadist Khaled Sharrouf, who posted the photo on Twitter with the caption 'That's my boy!'

Former drug addict Sharrouf, 33, used his brother's passport travel to Syria after being banned from leaving Australia because of the terror threat he posed.

Another photo shows him with his young sons wearing camouflage fatigues and holding guns.

Sharrouf, who has been diagnosed with schizophrenia, was among a group of nine men accused of stockpiling bomb-making materials and planning terror attacks in Sydney and Melbourne in 2007.

He pleaded guilty and was sentenced to four years in prison.

Australian police announced last month that they had arrest warrants for Sharrouf and his companion Mohamed Elomar, another former Sydney resident, for "terrorism-related activity."   

They will be arrested if they return to Australia.  

Australian Prime Minister Tony Abbott said in an interview that the photograph was further evidence of "just how barbaric" the Islamic State group is.  

The IS, which has been described as so brutal that Al-Qaeda sought to distance themselves from the group, has taken over large parts of Iraq and Syria.

Over the weekend, America launched airstrikes at the group in a bid to help besieged members of the Yazidi sect who had been told by IS to either convert to Islam or die.