The initial takeup of a mobile phone app authorities hope will improve the tracing of COVID-19 cases has been strong, the government says.

Called COVIDSafe, the voluntary app became available for download and registration on Sunday evening and has been backed by doctors, nursing, business and banking groups.

As at 7.30pm 28-04-20, "2.25 million Australians have now downloaded and registered", federal Health Minister Greg Hunt tweeted late Sunday.

Mr Hunt also said anyone concerned about privacy could use a fake name when they registered for the app.

"Yes you can - that's legally available," he said.

The Australian app is based on Singapore's Tracetogether software, which records the Bluetooth connections a phone makes with others so the user can give that data to state health authorities if they catch the virus.

While launching the app on Sunday, Mr Hunt said it will "save lives and protect lives".

"It is about assisting and finding those cases which may be undiagnosed in the community, helping people get early treatment, have early diagnosis and to ensure that our doctors and nurses, our health workers, our families and friends are protected," he said.

The government hopes a broader testing regime and the contact tracing app will lead to a relaxation of the economic shutdown sooner.

Prime Minister Scott Morrison told the ABC that only health authorities would have access to the data.

"It's another tool we need to get back to normal as much as we can," he said.

Australian Government Department of Health

@healthgovau

The #COVIDSafe app helps slow the spread of #COVID19. Having confidence we can find & contain outbreaks quickly means govts can ease restrictions while still keeping Australians safe. Downloading the app helps protect you, your family & friends.

He said the contact numbers picked up by a person's phone are only downloaded by a health officer when someone gets the coronavirus and gives permission.

"No other government agency can use this information, no one in the commonwealth government at all, and in state authorities, only the health officer can use it," he said.

"Not the police, not the welfare people, nowhere else. Just the health officer."

Labor health spokesman Chris Bowen said the app had been activiated under the Biosecurity Act as an interim measure, but expects it will be legislated when parliament sits in mid-May and that will be important to assure Australians of their privacy.

"I'd be happy to download the app," Mr Bowen told reporters in Sydney.

"The only people I've seen say that they won't download the app are Liberal and National MPs."

Australian Medical Association President Tony Bartone told reporters the app was an important part of Australia's response to the pandemic.

"The COVID-19 COVIDSafe app will assist in the contact tracing process, that laborious slow process which, together with the marvellous community response, has been implicitly responsible for reducing the spread of COVID-19 in the community and flattening the curve," Dr Bartone said.

Business Council of Australia chief executive Jennifer Westacott urged all Australians to download the app.

"The more Australians who download the app the safer we will all be and the more quickly we can begin to ease restrictions," she said in a statemenAustralian Nobel laureate and immunologist Peter Doherty said he would be signing up for it.

"Anything that helps us wrestle COVID-19 to the ground is a plus. Any privacy any of us had pretty much disappeared when we started using mobile phones, searching online, buying stuff from Amazon or whatever," he tweeted on Sunday.

New research from the Australia Institute shows that 45 per cent of Australians say they will download and use the mobile app, while 28 per cent say they won't. A further 27 per cent were unsure.