Australia's second largest city, Melbourne, will go back into a strict lockdown to prevent a second wave of Covid-19 infections from spreading across the country.

A total of five million residents in the metropolitan city will no longer be allowed to leave their homes unless it's for grocery shopping, caregiving, exercise or work starting from 11:59pm on Tuesday, July 7.

This drastic action was announced as authorities declared that it's clear "we are on the cusp of our second wave".

The measures are expected to remain in place for six weeks.

They come as the state of Victoria saw another record rise in daily coronavirus cases, with 191 new infections recorded for Tuesday.

The state reported its previous high of 127 new cases on Monday.

Of the 191 new cases detected on Tuesday, 13 came from the nine public housing estates under a "hard lockdown".

About 3,000 residents in the densely populated towers were suddenly put under a total lockdown on Saturday night.

They are not allowed to leave their homes for any reason.

So far, a total of 69 cases have been detected in these estates.

Authorities aim to test every single resident.

Eateries go back to delivery-only

Under the new lockdown measures, cafes and restaurants that were allowed to reopen weeks ago will return to take away and delivery only.

Beauty and personal services will be closed, as well as cultural and entertainment venues.

Schools will extend their holiday for another week, but senior secondary school students and students at specialist schools will return to school as planned on Monday.

"We know we're on the cusp of something very, very bad if we don't get on top of this," Victoria State Premier Daniel Andrews told reporters in Melbourne on Tuesday, describing the surge in case numbers as unsustainable.

"I think a sense of complacency has crept into us as we let our frustrations get the better of us. I think that each one know someone who has not been following the rules as well as they should have. I think each of us know that we have got no choice by to take very very difficult steps," Andrews said.

Australia carrying out precautionary measures

Victoria had previously reimposed local lockdowns on dozens of suburbs around Melbourne.

Authorities announced on Monday, July 6 the border between Victoria and New South Wales (NSW) -- Australia's two most-populous states -- will be closed on Tuesday night.

This effectively cuts off Victoria from the rest of the country.

Border restrictions will also apply to metropolitan Melbourne and Mitchell Shire, a regional area of Victoria.

"By putting a ring around metropolitan Melbourne, we're essentially putting in place a perimeter to protect regional Victorians," Andrews said in a statement.

Australia has recorded almost 8,700 cases and 106 deaths from the virus.

More than 2,800 people have been infected and 22 killed in Victoria alone.

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