Private businesses in Melbourne could soon play a key role in combating terror incidents in the city.

Victoria police are looking at adopting a model used by the New York Police Department, where security officials from office buildings, sporting venues and shopping centres would help identify any risks before events in the city.

The 'Shield' program was put in place in the wake of the 9/11 terror attacks, and if implemented in Victoria, would mean private business share confidential intelligence reports in order to thwart potential terror attacks.

The 'Shield' program was put in place in the wake of the 9/11 terror attacks. (Nine)

The burnt out vehicle of Friday's Bourke Street terrorist. (AP/AAP)

Meanwhile, nine key locations have been identified in Melbourne to receive urgent security upgrades.

These include Queen Victoria markets, Federation Square and Bourke Street; where work is this morning underway to install permanent stainless-Steele bollards.

Work begun on Flinders Street earlier in the week, where 50 bollards will be installed, and a further 190 public service speakers will be placed around the inner city.

(Nine)

This plan comes just days after Melbourne's CBD was once again brought to a standstill by Friday's lone wolf Bourke Street terror attack and a day after Bourke Street driver James Gargasoulas was found guilty of murdering six people in last year's rampage.

Earlier this week, Prime Minister Scott Morrison doubled down on calls for Islamic leaders to be vigilant and pass information about suspected terrorists to intelligence agencies, saying they "can't look the other way".

Mr Morrison dismissed as an "excuse" claims Friday's Bourke Street killer was psychotic, and abused alcohol and drugs.

Mr Morrison visited Melbourne yesterday after Friday's terror attack. (Nine)

"He was a terrorist," Mr Morrison said.

"This bloke, radicalised here in Australia with extreme Islam, took a knife and cut down a fellow Australian.

"I'm not going to make excuses for that.

"He was a radical extremist who took a knife to another Australian because he'd been radicalised in this country, and we can't give him excuses."

A supplied image obtained on Thursday, November 8, 2018 of proposed security upgrades for Flinders Street Station in Melbourne, Victoria. Work on more than 50 permanent bollards. (Nine)

Mr Morrison said Islamic community leaders and Imams had to do more to counter the threat within their own communities, saying they were being infiltrated, to recruit the young.

"They fill their heads with hate and vile rubbish," he said.

"These characters are targeted in who they come after. You need to know who they are. They are the infiltrators.

Mr Morrison dismissed as an "excuse" claims Friday's Bourke Street killer was psychotic, and abused alcohol and drugs. (Nine)

"They are a real risk to their own children.

"You can't look the other way. They are the ones who need to be weeded out. There can be no excuses."