According to Australian intelligence reports cited by The Independent, ISIS militants possess radioactive material, mostly stolen from government facilities, enough to build a large and devastating dirty bomb – a conventional explosive that is meant to disperse radioactive material over a large area.

In an interview with The Australian, Bishop also said that Islamic State (IS, formerly ISIS/ISIL) extremists "did not just clear out the cash from local banks" when they swept across large swathes of Iraq and Syria.

Bishop said that her statements stemmed from reports filed by the Australian Department of Defense, as well as the Foreign Office.

She added that NATO has expressed concern about the materials, which were reportedly seized from hospitals and research centers and would typically only be available to governments.

In addition to concern from NATO, Bishop also noted that the Australia Group – a 40-nation bloc dedicated to ending chemical weapons – held a session on the situation during a summit in Perth last week.

"This is really worrying them," she said.

At the Australia Group meeting, Bishop spoke about fears that ISIS is weaponizing poisonous gases such as chlorine.