Islamic State has begun to use the death of young Australian Jake Bilardi as propaganda, to shame boys from Muslim families into coming to fight in Syria and Iraq.

An online note, uploaded this week by apparent IS propagandist Abu Ismail, describes Bilardi as a "lion on the battlefield although he was at a young age and with a weak body".

IS "needs true men like him who wish to sacrifice this worldly life for the hereafter", Abu Ismail wrote.

"Brothers and sisters, this brother originated from an atheist family and ended up selling his soul to Allah for a cheap price, to defend this [community] and give victory to this religion, while you sit at home at the comfort of your family born into Islam and not doing anything to stop this oppression, what is the matter with you?"

The note says Bilardi's parents "basically went to war with him at home" over his conversion to Islam and that despite his parents' disapproval, he prayed regularly.

It also revealed that Bilardi had educated himself about jihad online by "following news from the mujahideen [Islamic fighters]".

Abu Ismail says that after a short period as a soldier in Syria, where he was a "lion", Bilardi "signed up for a martyrdom op" and was sent to Ramadi in Iraq, where he waited three months.

"He would always ask the amir [commander]  to push him up the list and make him carry out the martyrdom operation sooner."

During that time, Abu Ismail claims, Bilardi fasted every second day and was "known for his modesty".

IS has claimed that last Wednesday, Bilardi died in a suicide bombing in Ramadi at the wheel of a white Toyota. The Iraqi military has said the attack was futile, as it only injured a few soldiers.

Abu Ismail does not comment on the perceived success or failure of the attack, nor provide any further proof of Bilardi's death, though Australian authorities believe it is likely Bilardi died carrying out the suicide attack.

In the days leading up to his death, according to Abu Ismail, Bilardi was "full of happiness as he was finally going to meet his Lord and receive the great rewards promised by Him".