Millions of people across metropolitan Melbourne will return to strict stage-three lockdowns amid ever-spiralling COVID infections and hospitalisations.

Premier Daniel Andrews confirmed the return for the entire city on Tuesday afternoon.

The renewed lockdowns will start from midnight Wednesday and last for six weeks. They will also cover the residents of Mitchell shire, just north of the city.

“[The] cusp of a second wave [or] a second wave, what people want to call this is entirely irrelevant,” he said.

“We have to be realistic about the circumstances that we confront. We have to be clear with each other that this is not over. And pretending that it is because we all want it to be over is not the answer. It is indeed part of the problem.”

The drastic measures came as Victoria posted its single-worst day for new infections on Tuesday, with 191 confirmed cases. Victoria has 772 active COVID cases, the vast majority of them in Melbourne.

Tweet from @VicGovDHHS

The state’s active cases have risen by hundreds after nearly three weeks of double-digit daily cases.

“These are unsustainably high numbers of new cases. It is simply impossible with case rates at this level to have enough contact tracing staff, to have enough physical resources, no matter where they come from … to continue to suppress and contain this virus without taking significant steps,” Mr Andrews said.

“If we were to fail to take those steps, then it won’t be a couple of hundred cases per day, it will be many more than that and spiral well and truly out of control.”

The move comes less than a week after Victorian authorities locked down 10 Melbourne postcodes – home to more than 350,000 people –  until at least July 29. That was followed on Saturday by a hard lock down of nine public housing estate in the inner-city, and two more postcodes.

• NSW wants Victoria to pay for border closure

Tuesday’s decision means millions of Victorians will once again be restricted to home unless they are going to work or education, buying food or seeking or giving medical care.

Mr Andrews said Melburnians should remain in their primary homes and not take the new lockdowns as a chance to head to holiday houses. Daily exercise will also be allowed – but people are banned from leaving Melbourne to do so.

“This is, I know, further than what we went last time but we’re in a more precarious, challenging and potentially tragic position now than we were some months ago,” he said.

Regional Victoria has few coronavirus cases, although two suspected infections – one a visitor from Melbourne – were being investigated in the border city of Albury on Tuesday. There were also reports of suspected cases among a family of four who visited Port Fairy in southern Victoria.

“Vast parts of regional Victoria have no cases,” Mr Andrews said.”

“This is designed to keep it that way.”

He said he expected to announce eased restrictions for country areas soon.

• See more information about Melbourne’s restrictions here

School holidays, which were due to end on July 13, will also be extended by a week for the bulk of Victorian students. Only students doing VCE – mostly those in years 11 and 12 – will return on July 13.

Mr Andrews said Victoria Police would continue to enforce the restrictions.

“All of us have to be realistic about the circumstances we face. No one wanted to be in this position. I know there will be enormous amounts of damage that will be done because of this. It will be very challenging,” he said.

“Ultimately we have to take this as seriously as we take a bushfire. This is binary. It is life and death.”

Tweet from @AlboMP

Victoria’s latest cases

Among the 191 COVID cases confirmed on Tuesday are:

• 13 relating to the locked-down public housing towers (total now 69);
• 12 cases linked to the outbreak at Al-Taqwa College, in Truganina in Melbourne’s outer west (90);
• Four linked to the Northern Hospital in Epping (nine);
• One linked to Aitken Hill Primary School in Craigieburn, in Melbourne’s north (10);
• The remaining cases are linked to existing family clusters in suburban Melbourne – in Truganina, Patterson Lakes/Lysterfield, Fawkner and Sunshine West;
• One case in a staff member at Assisi Aged Care in Rosanna.