The Government wants 40 per cent of Australians to use its contact tracing app COVIDSafe, but questions remain about the technology's performance on iPhone.

Key points: If an iPhone is in low power mode, it reduces the background app refresh and may impact the ability to track contacts

If an iPhone is in low power mode, it reduces the background app refresh and may impact the ability to track contacts It's also been suggested the iPhone app may not work effectively if too many other Bluetooth apps are running

It's also been suggested the iPhone app may not work effectively if too many other Bluetooth apps are running Apple and Google are building their own contact tracing approach, which health authorities have been invited to build off

COVIDSafe aims to assist with the process of identifying those who may have been exposed to COVID-19 once someone is diagnosed.

"It assists in the early alert and finding of people who may have been in contact with a person who is positive with a diagnosis," Health Minister Greg Hunt said on Sunday afternoon.

Those with Android smartphones can use their devices normally while the app runs in the background.

However, if an iPhone is in low power mode, it reduces the background app refresh and may impact the ability to track contacts, according to a spokesperson for Government Services Minister Stuart Robert.

While the technical details are yet to be made clear, it's also been suggested the iPhone app may not work effectively if too many other Bluetooth apps are running.

COVIDSafe uses Bluetooth to record anonymised IDs from anyone you are within 1.5 metres of for about 15 minutes or more, if they also have the app.

But Apple's iOS rules typically prevent third-party apps from running in the background and broadcasting Bluetooth signals.

It's has been suggested the iPhone app may not work effectively if too many other Bluetooth apps are running. ( ABC News )

This is a privacy protection measure designed to protect users from being tracked without consent.

iPhone issues plagued Singapore's TraceTogether app, on which COVIDSafe was partially modelled. That country's app must be in the foreground on an unlocked iPhone to work efficiently.

TraceTogether has reportedly been downloaded by less than 20 per cent of the country, and its Apple App Store page is littered with reviews that complain of not being able to take phone calls while allowing the app to properly function.

Australia "had the benefit of seeing what happened [in Singapore]," Minister Hunt said today, and has "been able to work to ensure that that is not an issue in Australia".

He did not share exactly how Australia's approach differs from that of Singapore.

"We know that Apple, around the world, is working on that and we will provide those upgrades and updates as well," he said.

Dali Kaafar, executive director of Optus Macquarie University Cyber Security Hub, said the technical details of COVIDSafe still need to be picked apart — the Government is yet to release its source code for independent analysis.

"It would be interesting to hear from the Government whether this particular app is receiving a special permission or special treatment by iOS," he said.

"If you're trying to get a higher uptake for this app, we have to really [make] sure the app is working in the background with very little battery and energy usage."

Mr Robert previously gave an assurance that the source code would be published, subject to final advice from cyber security agencies.

Apple spokesperson Lucy Botham said COVIDSafe is available in accordance with Apple's iOS developer guidelines.

"We do not share details of our conversations with developers and have nothing further to add," she said.

The Apple and Google option

If iPhone users must remember to avoid low power mode or to close other Bluetooth apps while commuting, shopping at the supermarket or working in an office, the usefulness of the COVIDSafe iPhone app may be reduced.

All apps use battery, but Katina Michael, a professor at the University of Wollongong's Faculty of Engineering and Information Sciences, questioned whether COVIDSafe could be a particular energy drain because of its use of Bluetooth and the need for the app to always be on.

"Apple users may well give the app a go, but when they realise how fast the battery drains, they will quickly uninstall the app as it will inhibit the rest of their productivity on the device," she suggested.

In fact, Australia's contact tracing app is one of a number being built globally — prompting a debate about which design best preserves privacy, and whether such technology will truly assist medical authorities.

Apple and Google are building their own contact tracing approach, which health authorities have been invited to build off.

The Australian Government previously said it wouldn't be using their platform, but has now indicated the option will be examined.

"The Government will work with Google and Apple to investigate whether the new functionality announced by Google and Apple partnership is beneficial for the app performance," Mr Robert's spokesperson said.

France is now in a stand-off with Apple over its own contact tracing app.

It wants the company to remove the operating system block and allow its app's Bluetooth functionality to run constantly in the background.

"We're asking Apple to lift the technical hurdle to allow us to develop a sovereign European health solution that will be tied to our health system," France's Digital Minister Cedric O told Bloomberg.

When someone is diagnosed with COVID-19 in Australia and they consent, the encrypted IDs of people they've been in close contact with will be taken from COVIDSafe and uploaded into a Government database to be used by health officials.

The software base or application programming interface (API) from the technology giants, on the other hand, also uses Bluetooth but tries to avoid storing the data in a centralised way.

Users of the app must enter the mobile number to sign up. ( ABC News )

Each day, their system downloads a list of codes that belong to people who are confirmed COVID-19 cases. If there's a match, the user may be notified and told what to do next.

This approach has been endorsed by more than 300 academics around the world, who suggested in an open letter last week that sending data to a centralised location is less secure and could be subject to function creep.

"It is vital that, in coming out of the current crisis, we do not create a tool that enables large scale data collection on the population, either now or at a later time," the letter reads.

Minister Hunt said today that COVIDSafe data cannot be used for any purpose other than contact tracing during the COVID-19 pandemic.