Police have been told not to download the new NHS Covid-19 app on their work phone, with the new tool already hitting 12 million downloads.
Forces across the country were issued guidance telling them not to install the new app – though the National Police Chiefs Council insisted it was not as a result of security issues.
The warning came as Matt Hancock, the health secretary, claimed that the app had been downloaded more quickly than any other app in the history of the country.
But the success of the app has come with a range of concerns, including frustration that the app only works with more recent handsets and notifications that led some users to be needlessly concerned.
Now police officers have been advised not to install the app on their work devices – instead being encouraged to add it to their personal phones.
"Police forces use a variety of mobile devices with different system restrictions," the NPCC said.
"It is important that we have confidence that the NHS app will work for officers and staff consistently across the country, and it is for this reason that we have recommended that officers and staff download the app to their personal as opposed to work devices, rather than any suggestion of security implications."
It comes as Health Secretary Matt Hancock hailed what he called "the fastest download of an app in British history" having reached 12.4 million downloads by midday on Monday.
"I would urge everybody, including every single member in this House, to join the 12.4 million," Mr Hancock said.
The app uses Bluetooth technology to keep a tab of close proximity encounters with other people and informing them if one later tests positive for the virus.
The app is in the number one spot in both iOS and Android app stores.
Additional reporting by Press Association