The Australian government says it is unable to confirm reports that one of its most notorious militants, Khaled Sharrouf, has been killed in Syria.
According to Australian media, the so-called Islamic State fighter and two of his sons were killed by an air strike near Raqqa in recent days.
The government said it was "extremely" difficult to verify reports from Syria.
Sharrouf left Sydney in 2013 before heading to Iraq and Syria and becoming a prominent symbol of IS barbarism.
"If the reports are true, Australia will not mourn Khaled Sharrouf," Australian Attorney-General George Brandis said.
"He committed some of the most horrific crimes and waged war on Australians and our way of life."
Sharrouf, 36, was thought to have died in an air strike in 2015, but subsequent reports cast doubt on that.
Sharrouf was jailed in Australia in 2009 for his role in a foiled terror plot involving targets in Sydney and Melbourne.
In 2013, he used his brother's passport to board a plane leaving Sydney for the Middle East.
He was later joined by his wife, who died of health complications in 2015, and their five children, now believed to be aged between six and 15.
In 2014, he came to international attention when he posted graphic images on social media. One showed his young son clutching the severed head of a man reported to be a Syrian soldier.
"This image is really one of the most disturbing, stomach-turning, grotesque photographs ever displayed," John Kerry, then US Secretary of State, said at the time.
Authorities investigated claims in 2015 that Sharrouf had been killed alongside his friend, militant Mohamad Elomar, in a drone strike in the Iraqi city of Mosul.
However, it is now believed that only Elomar died in that attack.
Earlier this year, Sharrouf became the first Australian to be stripped of dual citizenship under new anti-terror laws in the nation.