Apple and Google say that the app broke an agreement made with Apple and Google.

App designers wanted to users to upload logs of venue check-ins - carried out via poster barcode scans -- if they tested positive for the virus. This could be used to warn others.

The update had been timed to coincide with the relaxation of lockdown rules. But the two firms had explicitly banned such a function from the start.

Under the terms that all health authorities signed up to use Apple and Google's privacy-centric contact-tracing tech, they had to agree not to collect any location data via the software.

As a result, Apple and Google refused to make the update available for download from their app stores last week and have instead kept the old version live.