Exclusive: Moment police swoop on Melbourne terror suspect

Vision has emerged of the moment heavily armed police pounced on the 20-year-old Somali-Australian accused of plotting a "catastrophic" terror attack in Melbourne's Federation Square.

In the exclusive amateur video, obtained by A Current Affair, Special Operations Group officers can be seen arresting Ali Ali outside a cafe in Werribee yesterday afternoon.

He's accused of plotting a mass shooting during New Year's Eve celebration, and has been charged with preparing to commit a terrorist attack and collecting documents to facilitate a terrorist attack.

Ali didn't apply for bail during a brief appearance in Melbourne Magistrates' Court this afternoon.

Authorities say they've been monitoring the man's alleged extremist leanings for several years.

During a media conference this morning, Victoria Police Deputy Commissioner Shane Patton alleged the young man's intentions were to cause mass carnage.

"This is a person who expressed an intention to try and kill as many people as he could through shooting them in Federation Square area on New Year's Eve," he said.

The man allegedly tried to obtain an automatic rifle to carry out the attack, but was unable to.

Police say there is no ongoing threat to the public.

Ali was remanded this afternoon and he's case was adjourned to March 13.

So far, 74 people have been charged as a result of 347 counter-terrorist investigations.