A Melbourne schoolboy who travelled to the Middle East to fight with Islamic State (IS) has reportedly died in a suicide attack in Iraq.
Jake Bilardi, an 18-year-old Muslim convert, left Australia last year and flew via Turkey to Iraq.
An image emerged on Wednesday purportedly showing him behind the wheel of a white van with the caption "may God accept him".
The Australian government said it had not been able to confirm the reports.
But Prime Minister Tony Abbott said it was "an absolutely horrific situation".
"It shows the lure of this death cult to impressionable youngsters," he said.
"It's very, very important that we do everything we can to try to safeguard our young people against the lure of this shocking alien and extreme ideology."
Australia estimates that 90 of its citizens are fighting for IS in Syria and Iraq, with 150 more at home sympathetic to the group.
The foreign affairs department said its "capacity to confirm reports of deaths in either Syria or Iraq is extremely limited".
Speaking to a BBC Newsnight reporter in December, Jake Bilardi had said he had travelled to Iraq to become a martyr, and wanted to die in a suicide attack.
The Age reported that it had identified the young boy in this picture as an 18-year-old from Melbourne
Bilardi (centre) was initially reported to be British when this image emerged in December 2014
"I came here chasing death, I might as well kill as many kuffar (infidels) as I can."
Asked if he would be allowed to change his mind if he wanted, he said: "Yes of course, it's your life, if you don't want to do it you just say so."
The teenager was identified by Australia's Fairfax Media last week. A member of an Islamic youth centre in Melbourne told Fairfax he was a "very quiet guy" who "stuck to himself".
The image published on Wednesday, that appeared to show Jake Bilardi, uses his Islamic name - Abu Abdullah al-Australi. The white van is similar to those used in previous suicide attacks by IS.
Reports suggested at least 13 suicide bombs were simultaneously detonated on Wednesday in Ramadi, the provincial capital of Iraq's Anbar province.
Tweets by pro-IS accounts appeared to link the Ramadi attacks to the teenager, as well as IS militants from Uzbekistan, Russia, Syria, Egypt, Belgium, and Morocco.
The coalition government made it a criminal offence earlier in March for Australian citizens to set foot in the IS stronghold of Mosul without a legitimate reason such as a visit to family.
Any Australian who travels to the city could face 10 years in prison.
Similar restrictions making it an offence for Australian citizens to travel to the Syrian province of al-Raqqa, another IS stronghold, were put in place in December.
Last week, two brothers were intercepted at Sydney airport last week suspected of attempting to join IS.
The boys, aged 16 and 17, raised suspicions as they attempted to pass through customs. They were later released to their parents without charge.
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