France’s digital minister has said its coronavirus contact-tracing app has been downloaded 600,000 times since it became available on Tuesday afternoon.
StopCovid France is designed to prevent a second wave of infections by using smartphone logs to warn users if they have been near someone who later tested positive for the virus.
But a last-minute launch delay led some citizens to download the wrong product.
England has yet to confirm when its own app will roll out nationwide.
Health Secretary Matt Hancock had originally said it would be by 1 June, and then later suggested it would be around the middle of next week.
But the BBC has learned that it is now unlikely to be before 15 June and could be as late as July.
That is in part because of delays in releasing a second version of the software to the Isle of Wight, where it is being trialled.
The update will add symptoms including the loss of taste and smell to a self-diagnosis questionnaire next week, or soon after.
It will also start giving at-risk users a code to enter into a separate website when they book a medical test. This will allow the result, saying whether they tested positive or negative, to be delivered back to them via the app.
Both the UK and France have created apps of their own based on a “centralised” design.
By contrast, Latvia, Italy and Switzerland have released apps based on a “decentralised” technology developed by Apple and Google.
Advocates of the centralised approach says it gives epidemiologists more data to analyse, helping them better target the contagion alerts. They are also not limited by rules imposed by the two tech companies, such as a ban on being able to gather location data.
Supporters of the decentralised model say it better protects users’ anonymity and privacy.
StopCovid France’s rollout has caused controversy.
Hundreds of academics signed a letter in April raising concerns that gathered data could be repurposed for mass surveillance purposes.
There was then a row over the government’s refusal to give MPs a vote on the matter, which was only resolved after ministers gave the Senate and National Assembly non-binding votes.
They both ultimately gave the app the green light. And the country’s data privacy watchdog also approved the rollout after carrying out its own review, although it did ask for some changes to the app’s wording.