Apple and Google have announced a partnership to build a system for tracking the spread of the new coronavirus.

Users will be able to opt into a system that tracks their location and proximity to others via Bluetooth technology. This data will initially be made accessible to official apps of public health authorities.

If a user reports that they have been diagnosed with Covid-19, the system will alert those who have been in close contact with the infected person within a certain time period. They will be given advice from a local health authority as to what steps to take, including self-quarantining.

The two tech giants will introduce iOS and Android APIs in mid-May and help health authorities to implement them into their own apps, which will be downloadable through the respective app stores.

In the months after that, the functionality will be built into the companies’ respective operating systems making it an option immediately available to everyone with an iOS or Android phone.

Public health organisations have identified "contact tracing" as a valuable tool to help contain the spread of coronavirus.

By finding as many people as possible that have been in contact with an infected person, and notifying them as soon as possible, steps can be taken to limit the spread of the virus. It can be an overwhelming task when done manually, and speed is of the essence, so an automated technological solution would be extremely helpful.

A number of leading public health authorities, universities, and NGOs around the world have been doing important work to develop opt-in contact tracing technology — the addition of Apple and Google gives a major boost to the large-scale roll-out of new tracking technology.

In a statement released by both companies, they emphasised the importance of maintaining strong protections around user privacy.

"Privacy, transparency, and consent are of utmost importance in this effort, and we look forward to building this functionality in consultation with interested stakeholders. We will openly publish information about our work for others to analyse," the statement says.

Both Tim Cook, CEO of Apple, and Sundar Pichai , CEO of Google, tweeted out the announcement on Friday.

"Contact tracing can help slow the spread of COVID-19 and can be done without compromising user privacy," said Mr Cook.

"To help public health officials slow the spread of #COVID19, Google & @Apple are working on a contact tracing approach designed with strong controls and protections for user privacy. @tim_cook and I are committed to working together on these efforts," said Mr Pichai.

The issue of privacy is at the forefront of many people's concerns about the use of tracking technology, whether users opt-in or not.

Jennifer Granick, the American Civil Liberties Union's surveillance and cybersecurity counsel, comments: "No contact tracing app can be fully effective until there is widespread, free, and quick testing and equitable access to healthcare. These systems also can’t be effective if people don’t trust them. People will only trust these systems if they protect privacy, remain voluntary, and store data on an individual's device, not a centralised repository."

The ACLU is also concerned that smartphone contact tracing methods could exclude vulnerable members of society that lack access to such technology, but are disproportionately impacted by the pandemic. The organisation recently published a white paper on the limits of location tracking technology in addressing the pandemic.

"To their credit, Apple and Google have announced an approach that appears to mitigate the worst privacy and centralisation risks, but there is still room for improvement. We will remain vigilant moving forward to make sure any contract tracing app remains voluntary and decentralised, and used only for public health purposes and only for the duration of this pandemic," Ms Granick adds.