A shocking image believed to show a Sydney boy holding a decapitated head in Iraq shows the ''barbaric'' nature of the Islamic State, Prime Minister Tony Abbott has said.
The image posed on Twitter shows a young boy, believed to be the son of Sydney jihadist Khaled Sharrouf, holding up the head of a slain Syrian soldier.
The image was taken in the northern Syrian city of Raqqa and was posted last week on the Twitter account of Sharrouf, Australia's most wanted terrorist who fled to Syria last year and is now a fighter with the Islamic State, formerly known as the Islamic State of Syria and Levant.
Abbott said on Monday that Australia would "gladly join the humanitarian airlift" in supplying aid to ten of thousands of Yazidi people and Christians trapped by the "terrorist army" in Iraq.
He said the Islamic State was trying to establish a "terrorist state" in Iraq and posed "extraordinary problems not just for the people of the Middle East but for the wider world".
"We see more and more evidence of just how barbaric this entity is," Abbott told ABC Radio.
"I believe there are more photographs in the newspapers in Australia today of the kind of hideous atrocities this group is capable of," he said.
The photo shows a boy, wearing a cap, checked pants and a blue shirt, struggling with both arms to hold up the head of the slain soldier.
The caption reads: "That's my boy!"
It is one of a several photos posted by Sharrouf, who security agencies believe travelled to Syria with his family.
Another photo shows Sharrouf also holding the decapitated head, while in another photograph, Sharrouf is dressed in camouflage fatigues and posing with his three young sons who are holding guns.
Defence Minister David Johnston said on Monday the photographs underlined why the government was moving to introduce tougher counter-terrorism laws.
"I'm obviously revolted by that and it underscores the importance of the counter-terrorism laws we are seeking to enact," Senator Johnston told ABC Radio.
But he stressed the bulk of Muslims were peaceful people.
Sharrouf, a convicted terrorist, is wanted by Australian Federal Police over crimes in Syria and Iraq, which include the shooting execution of a captured Iraqi official in the desert outside the Iraqi city of Mosul.
The 31-year-old previously was sentenced to five years and three months in prison in Australia for his role in the 2005 Pendennis plot. He pleaded guilty to possessing items, six clocks and 140 batteries, connected with the preparation of a terrorist act.
Late last year, Sharrouf left for the Middle East on his brother's passport.
He recently sent an extraordinary manifesto to Fairfax Media, threatening a terrorist attack on Australian soil and revealing he had been ''on the path they hate'' since he was 19.
He also criticised the government's hypocrisy in allowing Jews to fight for the Israeli Defence Force while banning Muslims from fighting in the Syrian or Iraqi conflicts.
"They fight us and harm us we will retaliate we will dedicate our lives to your unrest," he wrote. "We r not mad men or dysfunctional as they portray us to be [sic]. By Allah, we are the sane. Anyone who sees what is happening to the muslims [sic] around the world . . . and sits back and does nothing, he is insane."
He demanded the release of 12 Muslim prisoners and claimed he played the Australian Security Intelligence Organisation and police for fools while he was under surveillance.
Terrorism experts and authorities have cast serious doubt on the seriousness of Sharrouf's threats but say he has a tight social media network of followers who may be swayed by his extremist rhetoric.
After serving a four-year sentence for his role in the Pendennis terrorism plot, Sharrouf became a debt collector and claims he fooled authorities into believing he was not a jihadi. A court found he was diagnosed with depression in 1999 and schizophrenia in 2002, a fact he disputes.
"Let them know that I played the government there like ignorant children i was never mentally ill not then nor now [sic]," he wrote. "I seen them following me and I was working for Allah right underneath there noses [sic]."
-Sydney Morning Herald, With AAP