A 25-year-old man has been arrested and charged with allegedly supplying a firearm in a fatal siege in Brighton, which Prime Minister Malcolm Turnbull called an "act of terrorism".
Victoria state police said in a statement on their website that the man had been charged with four offences and would appear in court on June 14.
The deadly attack took place on June 6 in Australia's second-largest city with police shooting dead a gunman, Yacqub Khayre, after he killed a man in the foyer of an apartment block and held a woman hostage inside.
On Friday, a man was charged following a number of counter-terrorism raids in Melbourne's north that were linked to the siege.
Victorian Premier Daniel Andrews told Sky News on Friday, "We're obviously limited in what we can say, we don't want to put any of our operational staff in harm's way by speaking about these matters, but they [the raids] are in connection with the terrible tragic events of Monday in Brighton."
Turnbull said police were treating the siege as an "act of terrorism" after a claim by the Islamic State group that one of its fighters was the gunman responsible.