People waiting hours for COVID tests across Melbourne

Queues at COVID-19 testing sites have stretched back kilometres in Melbourne with some forced to close due to high demand.

The testing blitz came after multiple positive cases of the mutant UK strain of the virus were detected in hotel quarantine yesterday, including a staff member at the Park Royal.

The infected 26-year-old Noble Park man had been working as a resident support officer as part of the Australian Open quarantine program.

READ MORE: Australian Open hotel quarantine worker tests positive to coronavirus

The cases saw premier Daniel Andrews announce a snap new array of restrictions he said were much like "New Year's Eve" settings late last night.

He urged Victorians to get tested and today they were out in droves

MSAC stopped accepting drivers after the wait-time ballooned to four hours.

At the Springers Leisure Centre in Keysborough and Sandringham Hospital people were in three hour long queues.

READ MORE: Australian Open players will not get any 'special treatment' as up to 600 linked to tennis tournament told to isolate, get tested

In the morning, Swinburne University at Wantirna had two hour delays.

"We can't have people just stampeding through these places, it's got to be done carefully, slowly, meticulously," Mr Andrews said.

"I don't want a testing site to become a superspreading site ... so it's got to be done very carefully."

Tradie Mitch Prosser developed symptoms after visiting Brandon Park Kmart at the same time as the positive case.

"I went to Brandon Park on the weekend - just thought I'd come and get tested, it's the right thing to do," he said.

Yesterday, the government confirmed six cases of the UK variant were detected in return travellers at the Park Royal.

Late last night the hotel quarantine employee tested positive, meaning there was a high possibility of community transmission but so far all his close contacts have tested negative.

All positive cases are in isolation at a health hotel.

READ MORE: Victoria renews restrictions after hotel quarantine COVID-19 case

Mr Andrews said health authorities have not yet figured out exactly how the hotel quarantine worker contracted the mutant UK strain of coronavirus.

He said officials were doing "step-by-step painstaking detective work" to figure out how he caught the virus.

"The working theory and the assumption - I think it's a well founded one - is that he's got it in hotel quarantine, despite not having done anything to breach infection control protocols."