The amount Brits are using Facebook has plunged by more than a third over the past 12 months, new research indicates, in sharp contrast to the company’s official statistics.

The number of online interactions made on Facebook’s mobile app in the UK plummeted by 38pc between June 2018 and June 2019, according to the analytics firm Mixpanel.

Interactions, which occur when users click on a web link or advert inside the Facebook app, declined in seven of the last 12 months, with an average monthly fall of 2.6pc. That paints a very different picture from Facebook’s own numbers, which report a slow but steady rise in monthly active users across Europe.

User numbers have traditionally been considered a barometer of the company’s health. Last July, an unexpected drop in European users and gloomy guidance about future growth wiped more than $120bn (£95bn) off Facebook’s market value in a single day.

In October, Mark Zuckerberg, the chief executive, said Facebook’s audience in North America was now “pretty close to saturation” and that future growth would come from developing countries. Since then company executives have emphasised figures which measure how many people are using all its services, including the fast-growing Instagram and WhatsApp, rather than Facebook alone.