Melbourne's fourth coronavirus lockdown will extend for another seven days, though restrictions in regional Victoria are set to ease.

Melbourne's lockdown will be extended for another week, in an effort to stamp out an outbreak of a highly contagious and fast-spreading coronavirus variant.

Acting Premier James Merlino on Wednesday confirmed Greater Melbourne will remain in lockdown until 11.59pm on June 10.

He said the Indian variant of COVID-19 currently spreading in the community was "quicker and more contagious than we have ever seen before".

"If we let this thing run its course, it will explode," he told reporters.

"We've got to run this to ground because if we don't, people will die.

"If that happens, it's our most vulnerable - it's our parents, it's our grandparents, it's Victorians with underlying conditions or compromised immunity who will pay the price."

Melburnians will continue to have only five reasons to leave home: to shop for food and essential items, to provide or receive care, for exercise, work or study, or to get vaccinated.

Masks will also remain mandatory, though the travel limit for exercise and shopping will extend from five kilometres to 10.

Year 11 and 12 students will be able to return to face-to-face learning, and some outdoor work such as landscaping and painting can resume.

Restrictions will be eased in regional Victoria from 11.59pm on Thursday if there are no cases of community transmission.

The so-called "ring of steel" - a series of road checkpoints that stood between regional Victoria and Melbourne during last year's extended lockdown - will not be used to enforce the different restrictions.

Instead, police will patrol the state's roads, conduct spot checks in regional towns and use number plate recognition cameras to catch people breaking the rules.

Regional business owners will also be required to check customers' identification.

Victoria's Chief Health Officer Brett Sutton said the lockdown extension would ensure that any new cases likely to emerge are not creating more exposure sites and chains of transmission.

The state recorded six new locally-acquired cases on Wednesday, including a family of four who travelled to Jervis Bay in NSW, bringing the latest outbreak to 60 active infections.

It's not yet known how the family, from Melbourne's west, contracted the virus.

A second resident at aged care facility Arcare Maidstone has also tested positive, though the case will likely be included in Thursday's figures.

Arcare chief executive Colin Singh said the fully vaccinated 89-year-old man, who has been taken to hospital, was a cousin of the first resident who tested positive and resides in an adjacent room.

There are more than 5000 close contacts self-isolating as part of the outbreak and more than 350 exposure sites across the state.

Professor Sutton said about 10 per cent of current cases caught the virus through "fleeting exchanges" with infected people.

"We do have a suspicion that there has been transmission two hours after an infectious case has left an indoor enclosed space," he said.

"That's in the... measles category of infectiousness."

Prof Sutton said he had "great confidence" restrictions would be eased at the end of the week.

But Mr Merlino said even if all goes well, there will be no travel from Melbourne to regional areas over the Queen's Birthday long weekend.

To help soften the blow to business, the government is expanding its support package from $250 million to $460 million.

Mr Merlino again called on the federal government to provide wage subsidies to those affected by the extension.

Opposition Leader Michael O'Brien said the state government needed to urgently help small businesses and workers, who are "hanging on by a thread".

He also criticised the "apocalyptic" language used to describe the Indian variant and urged the government to release the public health advice given to justify the lockdown extension.

In the 24 hours to midnight Wednesday, 51,033 people were tested for COVID-19 and 20,585 were vaccinated.