Victoria has posted an enormous single-day record increase of 288 COVID cases on Friday, with authorities warning worse is yet to come for the virus-stricken state.

The leap dwarfs by nearly 100 the state’s previous highest single-day total of 191 and takes Victoria’s active COVID case tally to more than 1000.

It is also the highest daily total recorded anywhere in Australia since the pandemic began. Previously, the record was 212 cases recorded in NSW on March 27.

The number of Victorians in hospital has also risen, to 47. There are 12 patients in intensive care.

“I know there will be great concern about these numbers. People will feel deeply concerned to see that number as high as it is,” Premier Danie Andrews said.

He said the number of new cases proved the need for Melbourne and a neighbouring local government area to re-enter lockdown.

“We didn’t take that step because we didn’t have a problem, we took that step because we knew it would need to get worse before it got better, and that unless we took those steps we simply wouldn’t be able to bring a sense of control to this,” he said.

Chief health officer Brett Sutton said it was “a pretty ugly number”.

“It is an indication of the transmission that was occurring a week ago that is showing up in the numbers today, and we may well see it worsen before it gets better,” he said.

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Professor Sutton said infection numbers should start to plateau as the Melbourne-wide stage-three lockdown helped to control the spread of the virus.

“The effect of the lockdown, we will really only be seeing in the numbers in the next one-two weeks,” he said.

The leap has prompted authorities to recommend Victorians – especially those locked down in metropolitan Melbourne and the neighbouring Mitchell shire – should wear masks then they leave their homes.

Professor Sutton said a Lancet study had found masks could reduce transmission of the virus by up to two-thirds when worn across a broad section of the population.

“Those settings where you might be in close proximity with others are public transport, taxis, and Uber; shopping for food, shopping for goods, essential goods, visiting your GP – these are really important times to wear a mask, especially when you know that somebody has to be in close proximity to you, because you need to be there and you can’t distance effectively,” he said.

Melburnians have officially been told to wear masks when they leave their homes. Photo: Getty

Mr Andrews said the state had ordered two million reusable masks. “Our request, not an obligation” was for Victorians to start to wear them – and expect to do so for some months.

“This is not something that is going to be for a week or even six weeks,” he said.

“Masks, in those circumstances [when] you can’t maintain distance, will be a feature of our response to the pandemic for the foreseeable future, may many, many months.

“Any level of protection, if you can’t keep that 1.5 metres, is better than none.”

How-to guides for wearing and even making masks will be produced in coming days.

Friday’s enormous COVID tally came after more than 37,000 tests were done in Victoria on Thursday – another record.

“No one should underestimate how significant, how big a challenge we all face,” Mr Andrews said.

“It is very significant.”

The biggest increases in case numbers were in suburbs in Melbourne’s north, including Roxburgh Park and Craigieburn, and Truganina in the west, where the state’s largest cluster at Al-Taqwa College is located.