The abhorrent photo everyone is talking about today.

The boy in the photo is only seven years old.

He’s dressed as if going to a friend’s birthday party: checked shorts, casual sandals, a cap and a bright blue T-shirt.

But it’s what he’s holding in that has made this photo front page news today: it’s the severed head of a man, reported to be that of a Syrian soldier.

The photo, uncovered by The Australian, was posted to Twitter on Friday by Sydney man and convicted terrorist Khaled Sharrouf, alongside the chilling caption: “Thats my boy!”

Sharrouf is a suspected war criminal, wanted by Australian Federal Police over his crimes in Syria and Iraq,  The Australian reports.

The boy in the picture is his oldest son, who was raised in the suburbs of Sydney. The family are believed to have fled Australia and travelled to Syria in December last year, according to The Australian.

Sharrouf, who has previously tweeted photographs of decapitated heads on spikes, also uploaded a photo of himself posing with a severed head alongside the caption: ‘What a head’.

Another photo tweeted by the convicted terrorist showed him posing with his three young sons, clad in camoflague clothing and armed with machine guns, the Daily Mail reports.

The boy’s appear to be aged around four, six and seven, The Australian reports.

But it is the photo of Sharrouf’s oldest son that has provoked the most controversy today, with Prime Minister Tony Abbott telling ABC radio the picture encapsulated the true horror of which the Islamic State of Iraq and the Levant (ISIS) is capable.

“I believe there are more photographs in newspapers in Australia today of the kind of hideous atrocities that this group is capable of,” Mr Abbott said.

The gruesome image follows thousands of tweets by fanatical ISIS supporters bearing the hashtag #AmessagefromISIStoUS over the past few days. Those chilling tweets featured images of dead US soldiers and citizens, along with threats of further atrocities.

Jihadist group ISIS, also known as ISIL, was formerly known as the Islamic State in Iraq and Syria. It has announced the creation of a “caliphate” — an Islamic state led by a supreme religious leader — and is the group responsible for trapping tens of thousands of members of a religious minority on a mountain in Iraq’s north last week.

The UN condemned those attacks, saying ISIS may be accountable for crimes against humanity.