Over the weekend, media reports suggested that law enforcement could access people’s data on a case-by-case basis to ensure they were self-isolating if formally notified to do so.

But the government has denied that is the case, with a tweet from the app’s official Twitter page stating that the app “cannot be used to track your location, for law enforcement, or to monitor self-isolation and social distancing”.

All data on the app is stored on users’ phones, and the app cannot track your location. It works by recording people’s distance from other phones that have the NHS app installed.

The app, which was designed in collaboration with Google and Apple, is based on a decentralised model of data storage, after a centralised version of the app was abandoned earlier this year following a trial. The decentralised app has been downloaded 18m times since its launch in September.

A spokesperson for the Department of Health and Social Care said: “The NHS Covid-19 app is designed to the highest standards of data privacy and data security. App users are anonymous, all personal data is stored on the phone and is not shared with the government, NHS or law enforcement.

“It is a legal requirement for people who have tested positive for Covid-19 and their close contacts to self-isolate when formally notified to do so.”