The warning will be played on the public address system at 65 speaker locations from 11am.

“If you hear the test alert or notice an enhanced police presence in the CBD tomorrow morning, there is no cause for panic,” North West Metro Region Assistant Commissioner Stephen Leane said.

“The test of all 130 speakers at 65 sites across the city will run for approximately five minutes and the message transmitted will include a warning signal which clearly notifies the public that it is a test only.

“We will then conduct zone testing in different areas across the CBD until 11.30am, starting east of the CBD then moving to the west and southern parts of the city.”

Victoria Police said police officers would be present at each speaker site to provide reassurance and respond to any concerns community members might have.

Train, tram and bus passengers are also supposed to be notified before and during the test via the PTV and TramTRACKER apps, as well as onboard and platform announcements.

Social media posts will be issued by Victoria Police, the City of Melbourne, PTV, Metro, Yarra Trams and Emergency Management Victoria in relation to the test.

Victoria Police said the CBD Public Address System was a new option to alert the community about important safety information during a range of emergencies, including a major incident such as terrorism.

A further 60 speakers are being installed at 30 sites throughout the CBD.

“It is important to remember this is a test of the speaker system and that it is just one of the warning options available to police in these scenarios,” Assistant Commissioner Leane said.

“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.”

Tomorrow’s test follows a system demonstration in December.

For more information visit www.vic.gov.au/melbournesecurityupgrade.