Victoria is expected to announce more than 400 cases of coronavirus today, a record for the state.

Premier Daniel Andrews is set to face the media at 11am and announce 428 COVID-19 cases and reportedly more deaths.

There have been 4750 cases recorded in Victoria so far.

Victoria's previous biggest daily increase came yesterday with 317 new cases.

It was the largest increase in any Australian state or territory since the pandemic began.

Of yesterday's cases, 28 were linked to known outbreaks and 289 are under investigation.

Health Minister Jenny Mikakos labelled it a "very concerning number".

Australia has recorded a total 10,620 cases of COVID-19, with 3338 in New South Wales, 1071 in Queensland, 444 in South Australia, 646 in Western Australia, 228 in Tasmania, 113 in the Australian Capital Territory and 30 in the Northern Territory.

Meanwhile, a secret report by virus detectives into the source of the COVID-19 outbreak that has forced Melbourne into lockdown is being kept under wraps by the Victorian Government.

The renowned Doherty Institute, the medical research facility that convinced Prime Minister Scott Morrison to shut down the economy earlier this year to avoid a European-style outbreak, has revealed it cannot release new genomic sequencing because of a public inquiry into the bungled hotel quarantine mess.

But the decision has sparked fury in Victoria, because the taxpayer-funded research explaining how the outbreak escaped hotel quarantine and forced its way into multiple public housing blocks in Victoria is critical to understanding why millions of Melburnians are now under lockdown.