Facebook is changing the way its users send instant messages, as the social network confirmed it was removing the feature from its main mobile app.
Users will be required to use another of the company's official apps, Messenger, to send and receive instant communications on mobile devices like iPhone.
A spokesman said: "Today we are starting to notify people that messages are moving out of the Facebook app and over to the Messenger app. To continue sending messages on mobile, people will need to install the Messenger app."
According to the social network, this move should improve chat abilities for many users, with Facebook data suggesting replies are 20% faster on Messenger.
Earlier this year, Facebook acquired instant messaging service WhatsApp for 19 billion dollars (£11 billion), with many industry experts suggesting at the time that the Messenger aspect of Facebook could be phased out and replaced by WhatsApp.
However, this latest shift in software layout shows that Facebook is keen to make Messenger a central part of the social network's operations, while WhatsApp continues to operate independently.
Last month, Facebook updated its messaging service to better support group messages, a sign that the company has been learning from the WhatsApp acquisition as a similar feature is a prominent part of that service.
Currently, when users with both the official app and Messenger installed on their device try to use messages, they are automatically redirected to Messenger, so they will be unaffected by the change. Those without the app will be prompted to download it upon trying to use the chat function on mobile.
According to Facebook, this new set-up will be rolled out over the next two weeks, starting in Europe, where some have already begun to receive notification of the change.
The company also believes that taking messages out of the Facebook app will enable the technology giant to "focus on making Messenger better for everyone rather than working on two messaging experiences".