Scientists and researchers from 27 countries expressed concerns over privacy in using contact tracing apps to monitor the Covid-19 (coronavirus) outbreak and urged governments to avoid misuse by ensuring decentralisation of collected data.

In an open letter, nearly 300 academics expressed concerns some technology innovations “may, via mission creep, result in systems which would allow unprecedented surveillance of society at large”.

They gathered around a push for apps to use Bluetooth-based technology for automated contact tracing instead of tools based on sharing geolocation, as the latter carried privacy risks due to the data being sent to a centralised location.

However, the group warned some Bluetooth-based proposals could also enable surveillance by governments or the private sector and advocated for the development of a tool which does not enable large scale data collection at any given time.

The group also said apps should not access a user’s “social graph”, information which shows who they physically meet and when, as this posed a risk hackers could spy on people’s activities in the real world.

“We urge all countries to rely only on systems that are subject to public scrutiny and that are privacy-preserving by design” to ensure data protection is upheld, the group said.

The academic community called for contact tracing apps to be voluntary, transparent and used only to support public health measures for the containment of the pandemic.

In the letter, the group also welcomed efforts by Apple and Google to jointly build contact tracing technology, unveiled last week.

Concerns over data security in the use of technology for combatting Covid-19 were also addressed by the European Data Protection Supervisor, which called for the development of a single mobile app across the European Union in line with existing privacy regulations.