Prime Minister Scott Morrison has called on Muslim leaders to take “special responsibility” for stamping out radicalism in their communities, saying they must be proactive and “call this out for what it is”.

Speaking on Saturday in the wake of Melbourne's Bourke Street attack, Mr Morrison pointedly said that Islamist extremism, rather than a corruption of any other religion, presented the most dangerous form of radicalism in Australia.

Opposition Leader Bill Shorten meanwhile said Australia needed to be “ruthless” against people who carried out violence in the name of a “twisted, perverse” version of religion but cautioned against generalising about Muslims.

The question of how political leaders discuss Islamist extremism has been a controversial one in recent years. Tony Abbott as prime minister angered many Muslim community leaders by once questioning their dedication to curbing extremism, while his successor Malcolm Turnbull deliberately toned down his rhetoric, arguing that Muslim communities were key allies in the fight against radicalisation.