No plans to delay the further easing of restrictions in Victoria despite experiencing an increase in coronavirus cases.

State of Victoria recorded 13 new cases of coronavirus overnight, including five people who were contracted security guards working at the Stamford Plaza hotel in Melbourne.

Victorian health authorities believe physical-distancing breaches by some security guards at a Melbourne hotel used to quarantine returned travellers may have contributed to an outbreak that has now grown to seven cases.

Today's data marks the third day in a row where more than 10 cases have been recorded in a single day in Victoria.

Eighteen new cases were announced on Thursday and 21 on Wednesday.

The new cases also included two people linked to a family outbreak, one close contact of a known case associated with the Rydges on Swanston Hotel outbreak, and one returned traveller in hotel quarantine.

Three of the new infections were detected through routine testing.

This  morning Victorian Premier Daniel Andrews says the state will press on with its plans to further ease coronavirus restrictions next week, despite an apparent increase in community transmission of COVID-19.

The Premier said there were no plans to delay the further easing of restrictions planned for June 22, but said officials would review restrictions every day.

"It's all based on what the virus is doing in the Victorian community, how much community transmission there is, how confident we are that a second wave can be avoided," he said.

"And at this stage, we remain confident of that. But we're going to keep working hard to make sure that everything we do minimises the chances of a second wave."

Fifteen of the 21 cases reported on Wednesday were returned overseas travellers already in hotel quarantine.

Under the border restrictions agreed to by National Cabinet, people returning to Australia have to quarantine for 14 days in whichever city they land.

And with most international flights landing in Sydney and Melbourne, that means NSW and Victoria have been getting almost all the returned travellers who have already been infected overseas.

Victoria's Chief Health Officer, Brett Sutton, said "a couple of hundred" overseas travellers arrived at Melbourne Airport each day, with the number getting closer to 1,000 on some days.

"We all recognise that those who [test positive] in quarantine really shouldn't be counted for any jurisdiction," he said.

"It's not about transmission that's occurring in those jurisdictions.

"They're all international cases who happen to be hosted mostly in New South Wales and Victoria."

Of the 81 new infections recorded in the week to Thursday, 35 were returned travellers in hotel quarantine.

Professor Sutton said any increase in the numbers of international travellers testing positive to coronavirus was a reflection of what was happening globally.

If a lot of people are being infected in a country, more Australians are likely to bring the virus with them when they come back home.

A large number of the returned travellers were from the Indian subcontinent, Health Minister Jenny Mikakos said on Wednesday.

"Countries like India, Bangladesh and Pakistan are experiencing exponential growth in confirmed cases at the moment, and obviously that's impacting on the increase on our numbers who are in hotel quarantine," she said.

Victoria has accounted for most of the country's recent COVID-19 cases, while many other states and territories have gone weeks without a new infection.

Epidemiologist Ivo Mueller, from Melbourne's Walter and Eliza Hall Institute, said it was expected to see the variability of cases going up and down as the virus spread in the Victorian community.

"Whether this indicates a blip and just a spike in the data or a change in the trend, it's too early to say," he said.