THE Melbourne schoolboy turned "white jihadi" fighting with Islamic State in Iraq self-radicalised over the internet "out of his hate towards the media and government" of western countries, his best mate at school has revealed.

The friend, who does not want to be named, said he had no warning, but was not surprised when high school dropout and Muslim convert Jake Bilardi became a fighter for the radical Islamic group.

The young Australian Jake Bilardi alongside two Islamic State members. Credit:Twitter

Fairfax Media revealed on Monday that the 18-year-old Mr Bilardi had travelled to fight after dropping out of high school.

Mr Bilardi was an "intelligent teenager [who] spent the majority of his time researching political truth" before becoming "more involved in hating public media and the western government", the friend said.