A 65-year-old Melbourne man has been arrested after allegedly joining ISIS and distributing instructions for carrying out a mass-casualty attack. Authorities say he pledged allegiance to the group while remaining in Australia and acted as an online propagandist, making the case significant because of the scale and nature of the alleged extremist activity.

Counter-terror police allege the man shared about 10,000 files, including videos, images and messages depicting executions, torture and ISIS propaganda. Investigators reportedly began a covert inquiry in 2021 and monitored him for several years; he is expected to face charges of membership of a terrorist organisation and online propaganda activities.