A man has been arrested and a fake shotgun found during dawn counter-terrorism raids in Melbourne linked to the Brighton siege.
About 150 state and federal police and ASIO agents raided properties around the city in a bid to find out who gave Yacqub Khayre the gun he used to kill a man and injure three police officers on Monday.
Properties in Ascot Vale, Glenroy and Gladstone Park were raided on Friday about 5am, with a 32-year-old man taken into custody and two others, aged 31 and 51, interviewed.
"I want to make perfectly clear, we haven't yet uncovered anybody with links to terrorism who are associated with the offender from the Brighton attack," Victoria Police Deputy Commissioner Shane Patton told reporters on Friday.
"We believe these persons may be involved in the provision of firearms in respect to this matter that were used by the offender.
"They are not persons of national security interest. They are, however, persons who are known to us through their criminal history."
Entry was forced at the Ascot Vale flat, which had no one inside, and police are currently searching it for evidence.
Australian Federal Police (AFP) attend an address at Ascot Vale, Melbourne, Friday, May 9, 2017. (AAP) Source: AAP
At a second raid in Glenroy, five people were in the house and police took a 32-year-old man into custody, where he is currently being interviewed by the Joint Counter Terrorism Team.
He suffered a graze to his face during the arrest, police say.
Police are speaking to a father and son in relation to the Gladstone Park raid, where the imitation shotgun was found.
The raids relate to "aiding and abetting commission of engagement into terrorist acts".
A witness said at least 20 police had been "running around" on a major road, including Special Operations Group officers.
Premier Daniel Andrews said the raids are connected to the siege in which Khayre shot and killed Chinese-born Kai Hao and held an escort hostage before dying in a hail of bullets.
"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 are in connection with the terrible tragic events of Monday in Brighton," Mr Andrews told Sky News.
At least half a dozen officers remain at the Ascot Vale unit bagging items as evidence, while AFP officers are at a property in Flemington.
Others officers are inside the home on Churchill Ave, putting evidence into bags.
A crime scene has been established around a black Toyota Celica without number plates and a blue Mazda 3, while a police helicopter hovers above Flemington.
