Son of Australian terrorist Khaled Sharrouf poses in graphic photo

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 reportedly shows.

NSW Police yesterday 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 said.

"The current national terrorism threat level remains at probable."

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.

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

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.