Police officers help the coroner remove a body at the scene of a hostage situation in the Melbourne suburb of Brighton. Pic/AFP

Australian Prime Minister Malcolm Turnbull said on Tuesday police were treating a deadly siege in the city of Melbourne as an "act of terrorism" after a claim by the Islamic State group that one of its fighters was the gunman responsible for it. Police shot dead the gunman, Yacqub Khayre, who they said had a long criminal history, on Monday after he killed a man in the foyer of an apartment block in Melbourne and held a woman hostage inside.