Almost a third of returned travellers in hotel quarantine in Victoria are refusing to be tested for coronavirus, as infections in the state continue to soar.
Deputy Chief Health Officer Annaliese van Diemen said about 30 per cent of international travellers are refusing to be tested, despite multiple offers during their 14-day stay.
"I believe that not everybody who has been offered testing has taken it up," Dr van Diemen said on Friday.
"We're getting about 70 per cent of people uptake tests."
Chief Medical Officer Brendan Murphy said people in hotel quarantine need to be tested for the virus at the start and end of their stay.
"That 30 per cent is quite a high rate, other states haven't seen the same rate of refusal," he told reporters in Canberra on Friday.
"But states have the powers ... to say to someone, 'well, we won't let you out of quarantine until you've been tested and had a clear test'.
"We will ... make sure that people understand before they come that this is a requirement. I think most people will cooperate with that arrangement."
Meanwhile, Victoria recorded 30 new COVID-19 cases on Friday as the state racked up a 10th day in a row of new cases in the double-digits.
Of the 1947 total cases, 183 are active including six people in hospital.
Typical of the national trend over the past 10 days, there only four other new cases throughout the rest of Australia on Thursday, all in NSW.
Seven of Friday's new Victorian cases are linked to known outbreaks, five are in hotel quarantine, five came from routine testing and 13 are being investigated.
There's been an increase of 20,000 tests since Thursday, bringing the total tests in Victoria to more than 736,000.
The state is concentrating its testing efforts on 10 suburbs with high cases of community transmission: Keilor Downs, Broadmeadows, Maidstone, Albanvale, Sunshine West, Hallam, Brunswick West, Fawkner, Reservoir and Pakenham.
Public health officials are doorknocking the streets of the six local government areas identified as COVID-19 hot spots to ensure residents are doing the right thing.
These areas are the Melbourne municipalities of Brimbank, Cardinia, Casey, Darebin, Hume and Moreland.
Almost 5000 thermometers are also being shipped to holiday spots by the state government before the school holidays begin.
Meanwhile, dozens of Centrelink contract staff who live in the state's six hot spot areas have been stood down.
The contract staff are paid directly by labour-hire providers, including Chandler Macleod.
Chandler Macleod executive general manager Nick Gabrielidis told AAP a client decided to stand down staff living in the hot spots, on the advice of the Australian Health Protection Principal Committee.
The general manager of Centrelink's parent agency Services Australia, Hank Jongen, said fewer than 100 staff who live in the areas work outside them.
The workers have been paid for their rostered shifts on Wednesday.
As the state's cases climb, up to 200 specialist medical and support personnel from the Australian Defence Force will be called in to help with the testing blitz from Saturday.
The number is revised from the 1000 the government earlier requested.
Opposition Leader Michael O'Brien labelled the government's handling of the crisis "chaos".
"A few days ago, the premier said they didn't need ADF personnel. Then they were desperately asking for it, they were proud they were going to be coming, and now they're turning them away," he said.
More than 1700 people have recovered from the virus in Victoria, while 20 have died.