Facebook is to switch off the messaging service in its mobile app, meaning users will have to download the Messenger app.
The social networking giant has notified users in some European countries that they won't be able to message friends through the Facebook app in two weeks' time. This will roll out to every country in the near future.
Users will have to download Facebook's chat app Messenger for iOS or Android. The main Facebook app's messages button will remain, but will send users to Messenger when in use.
According to The Verge, this won't affect lower-end Android devices due to memory constraints, and Windows Phone and tablet users will also still see messages inside the Facebook app.
Meanwhile, Facebook's big-money acquisition of WhatsApp was recently challenged by privacy campaigners in the US.
The company has come under pressure to declare what it plans to do with the messenger service's personal data.