Australia’s prime minister has said the deadly Sydney cafe siege may have been preventable, as the chorus of critics demanding to know why the gunman was free on bail despite a string of violent charges grew louder.

Australia’s prime minister has questioned why someone with such a “long and chequered history” as Sydney siege gunman Man Horan Monis was at large in the community.

Man Haron Monis was an Iranian refugee known for sending hate mail to the families of Australian soldiers killed overseas and facing several charges of sexual assault.