Anti-lockdown protesters gather in Melbourne CBD

Victoria Police have vowed to take action after thousands of anti-lockdown protestors have marched through Melbourne today, defying current public health orders.

Demonstrators sprawled across the city and outnumbered the hundreds of police officers in attendance, to oppose the current COVID-19 lockdown.

Protestors chanted "free Victoria" and lit flares on the steps of state parliament, as many marchers became aggressive, prompting police to call in the mounted branch.

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The protests came after the state recorded 12 new cases today, as residents wait anxiously to find out whether the state's lockdown will be extended.

Victoria's Chief Health Officer Professor Brett Sutton expressed his disapproval of the protest activity on Twitter.

"We can all argue the merits or otherwise of various approaches to managing transmission, but let's not pretend that 'marching for freedom' will actually deliver the precious freedom that we all need and desire," Professor Sutton said.

Victoria Police assistant commissioner Luke Cornelius said he was disappointed to see " so many people blatantly disregard the Chief Health Officer directions (and) putting the health of Victorians at risk".

"Victoria Police supports the right to protest but now is not the right time during a global pandemic and when the state is in lockdown," Assistant Commissioner Cornelius said.

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"The event organisers were not cooperative with police nor would they consider moving the protest to a later date when it would be safe to do so.

"As a result, we had to roster hundreds of police to this event because of their selfish actions and blatant disregard of others.

"This is not where we want to be allocating our valuable resources - they should be in the community keeping people safe - yet we continue to do so because of the selfish minority."

Victoria Police will review all video footage from today's protest to identify "as many protesters as possible so that appropriate action can be taken against them".

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"We will not stand by while selfish people deliberately choose to put every Victorian at further risk of the spread of the highly contagious and dangerous Delta variant," Mr Cornelius said.

"It beggars belief that the protest today could, if mass spreading occurs, result in an extension of the very thing they are protesting for: an end to the current lockdown and a reopening of business, which is something we are all working so hard to achieve."