Alarms will sound through Melbourne CBD on Tuesday as part of the first large-scale test of a new anti-terror speaker system.

There will be a high police presence at 65 sites across the CBD for the trial between 11am and 11.30am.

Announced in December, the network of loudspeakers is intended to help the response to any future attack like the deadly Bourke Street rampage.

North West Metro Region Assistant Commissioner Stephen Leane said people traumatised by the Bourke and Flinders Street incidents should seek support during the trial on Tuesday.

“I’d urge you to be aware and to make sure you’re in a safe place and being around people that can look after you [on Tuesday] so you can have a good day,” he told reporters on Monday.

The speakers will initially be tested as a group before being individually tested. A warning message will play over the speakers alerting Melburnians of the test, before a loud siren will sound.

“We’re hoping the system will work most effectively. It is a test, so if we have any problems it’s better to find out [on Tuesday] than any other time. They will be very loud.”

Mr Leane hoped workers in high-rise buildings and those who’ve experienced bushfire warnings would be used to similar emergency alarm systems.

“We’re hoping it’ll be a very simple process and doesn’t interfere with people’s day-to-day activity.”

It follows an initial test at the State Library in December when the rollout began. A total of 190 speakers will be installed at 95 locations in Melbourne’s CBD by the end of the year.

They’re in place at crowded areas like Bourke Street Mall, Flinders and Swanston streets, with more to be added at Southbank and Crown Casino.

Victoria Police considered using the system during the Flinders Street incident in December, but decided against it.

“It will be used in a critical incident if we have a need, like a Bourke Street [incident]. We thought through it in Flinders Street, we didn’t find the need to use it. But if we need to give a community warning at any circumstances then we can use it,” Mr Leane said.

It could also be harnessed during events like New Year’s Eve when there is a risk of crowd crush.

During an incident, the speakers would play a short announcement, alarm and instructions.

“That may very well be ‘stay in place’, or that may very well be just to be aware there is a police incident occurring at a particular location.”

Mr Leane said the network of loudspeakers was just one of the warning options available to police.

“We can also communicate rapidly via SMS and our social media channels including Facebook and Twitter, which would be regularly updated during a critical incident.”

He said concrete bollards around the city would be replaced with permanent infrastructure like steel bollards in coming months.