An Australian teenager who ran away from his Bankstown family home in June has surfaced in a chilling Islamic State video threatening Tony Abbott and vowing to fight until the militant group has conquered the West.

Abdullah Elmir, 17 appeared in the video posted on the internet on Monday night under the nom de guerre "Abu Khaled from Australia". He is dressed in military gear and holding a rifle, standing among several dozen fellow jihadists.

Speaking for a little under two minutes directly to the camera, Elmir baits the United States, Britain and "especially … Australia" to throw everything they have militarily against the Islamic State group, which has seized large tracts of territory across Syria and Iraq.

He then vows the group will keep fighting until it has raised the black flag of the Islamic State above the White House and beheaded "tyrants" – apparently referring to Western leaders including Mr Abbott.