WARNING. Graphic image.

Australian terrorist Khaled Sharrouf has again used one of his children in a graphic propaganda image for the Islamic State group.

The photo shows Sharrouf’s youngest son, aged six, standing in front of a man’s body which has been strapped to a metal cross with cable ties.

A sign hanging from the man’s neck reads: “The Crime: Collaborating with Christians. The Punishment: Execution”, the image obtained by Seven News shows.

The boy featured in the photo is believed to be a son of Australian terrorist Khaled Sharrouf. Photo: Channel Seven

NSW Police on Sunday confirmed counter-terrorism police were aware of a photo “depicting a minor making threats in the name of ISIS”.

“The Joint Counter Terrorism Team is investigating the image, however, there is no specific threat,” a police spokeswoman told AAP in a statement.

“The current national terrorism threat level remains at probable.”

Prime Minister Malcolm Turnbull condemned Sharrouf’s “despicable” use of his child in the image.

“That is the depths of barbarity, of cruelty, of savagery, that ISIL, or Daesh, have sunk to,” The Prime Minister told reporters in Canberra on Monday.

“That is why we are committed, with our allies, to destroy ISIL in the field.”

It’s not the first time Sharrouf – who left Australia for the Middle East to become a IS fighter in 2013 – has used his children in this way.

A video featuring his youngest son wearing a suicide vest and threatening to murder Australians emerged just last week.

Another of Sharrouf’s sons – then aged seven – has also been shown in a photograph holding the severed head of a slain soldier.

Mr Turnbull said security agencies were leaving no stone unturned and would protect Australians from people who returned from the conflict zone.

“If they are adults, they will obviously be prosecuted to the full extent of the law. If they are children, they will nonetheless also be given the closest attention.”

Sharrouf’s wife, Tara Nettleton, died in 2015, leaving their five children in the Middle East.

Ms Nettleton’s mother Karen has tried unsuccessfully to bring the children back to Australia.

The revelations come amid reports former jackaroo-turned-jihadi, Guy Staines was killed by a US-assisted air strike in the past two weeks.

The NSW man, who converted to Islam in Goulburn’s Supermax prison, is believed to have left Sydney for Syria or Iraq last year.