Authorities in Melbourne have arrested a 20-year-old Australian citizen, who they allege was planning to launch an attack during New Year's Eve celebrations.
Ali appeared before the Melbourne Magistrates' Court, where he was charged with preparing to commit a terrorist attack and collecting documents to facilitate a terrorist act.
Deputy Commissioner Patton would not disclose how the man became a person of interest, but said more than 200 police across Victoria Police, the Australian Federal Police and the Australian Security Intelligence Organisation had been involved in the investigation.
Patton said the purported plan included firing into crowds during New Year's Eve festivities at Melbourne's Federation Square.
Patton said Ali, a known extremist and a sympathizer of the Islamic State group, had been having face-to-face meetings about getting a gun.
The arrest is not linked to any previous raids or terror arrests, police said.
Keenan urged the public to continue with their usual routines over the period and expect to see a heavy police presence.
Police arrested the man - a Muslim born to Somali parents - after he attempted to purchase an automatic rifle.
Two other locations were searched on Monday - his place of work and relative's home.
Since September 2014, when the national threat terrorism level was raised to "probable", the AFP has worked with its state and territory partners to thwart a number of plots.
Police said he would be charged Tuesday with terrorism offences, which carry a maximum penalty of life in prison.
A man who was reportedly planning mass shooting in Melbourne Square on New Year's Eve, was arrested by the Australian police.
IEDs in Melbourne, Aug 2016: Counterterrorism police disrupt an alleged domestic terrorist attack in Melbourne, potentially involving improvised explosive devices.
The man had allegedly obtained an al-Qaida manual from the internet with instructions on staging a terrorist attack and how to operate a gun.
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