UPDATE: Ballarat's top police officer says police will work through requirements for Operation Sentinel for officers but promises no changes to response times in the Ballarat region.
Inspector Jenny Wilson said police would discuss as a statewide body what would be required as the metropolitan enters stage three lockdown measures, but regional areas, except those living in the Mitchell Shire, will remain exempt.
"There's a number of policing operations across the state in which we're required to provide some resources to during the state of emergency," Inspector Wilson said.
"But there will be no changes to responses locally and current operational measures will remain in place."
It comes as Victoria's Chief Commissioner Shane Patten has promised there won't "be a ring of steel" around Melbourne.
"It won't be an absolute ring of steel, but there will be a significant police presence and a whole amount of those main arterial roads," Chief Commissioner Patton said.
More than 250 members of the Australian Defence Force will join Victoria Police in enforcing the lockdown. Police have the power to issue on-the-spot fines of up to $1652 to individuals breaching the chief health officer's directives.
"The window of police discretion is closing," he said.
"We've done this before in restrictions we've been through. People know what to do. They know what to expect."
EARLIER: The Victorian government announced a return to Stage 3 COVID-19 restrictions for metropolitan Melbourne and the Mitchell Shire on Tuesday afternoon.
Premier Daniel Andrews flagged roadblocks and "command centres" to ensure the boundary between metropolitan Melbourne and regional Victoria was not breached illegally.
He described the regional Victorian-Melbourne border as a "hard boundary".
Hundreds of Australian Defence Force troops have been deployed to help ring fence Melbourne.
Mr Andrews has asked the prime minister for 260 ADF personnel to help with on-the-ground support for putting closures in place across Melbourne.
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While he stopped short of saying every car would be stopped and checked, he insisted there would be a heavy defence presence.
"The ADF and Victoria Police will be out there to move sure we don't have the virus travelling to regional Victoria," Mr Andrews said on ABC on Wednesday morning.
"The last thing anyone wants is to see the virus travel to other parts of the country."
It comes on top of those already deployed to guard the Victoria-NSW border, which is now closed indefinitely.
These troops will support police operations, without directly involving themselves in law enforcement.
Victoria Police have confirmed they will use booze buses and mobile police facilities to monitor the border between locked down and non-locked down areas.
These have been used in several Melbourne postcodes which returned to Stage 3 restrictions last week.
A Victoria Police spokesperson said the monitoring facilities would be deployed in and around metropolitan Melbourne and the Mitchell Shire, so police could randomly check on drivers and passengers to explain their reason for travel.
These will change locations during each shift. Police will also patrol other areas of the state in vehicles and on foot.
The new restrictions means residents of metropolitan Melbourne and the Mitchell Shire will only be able to leave their house for essential shopping, care, daily exercise, and work or study.
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