Video report by ITV News Correspondent Sejal Karia
Facebook plans to integrate its Messenger service with Instagram and WhatsApp.
All three services will continue to function as separate apps, but behind the scenes their functionality will be linked, the New York Times reports.
This will mean a Facebook user could send a message to someone who only has a WhatsApp or Instagram account and vice versa.
The project is still in the early stages and is planned for completion by the end of this year or in early 2020, four people involved in the work told the paper.
They said Facebook boss Mark Zuckerberg has ordered all of the apps to incorporate end-to-end encryption which protects messages from being viewed by anyone except the participants in the conversation.
According to the unnamed sources, by linking all the apps together, Mr Zuckerberg hopes to keep billions of Facebook users within the social media's ecosystem and away from rival messaging services such as Apple and Google.
It is also a route to generating revenue from Instagram and WhatsApp which, despite having millions of users, make little money.
The insiders said that increased interaction with Facebook’s apps could boost advertising revenue or add new services to make money.
In a statement to the New York Times, Facebook said it wanted to “build the best messaging experiences we can; and people want messaging to be fast, simple, reliable and private.”
It added: “We’re working on making more of our messaging products end-to-end encrypted and considering ways to make it easier to reach friends and family across networks.”
Mr Zuckerberg bought Instagram and WhatsApp in 2012 and 2014 respectively and vowed to keep them as autonomous companies.
His apparent U-turn to merge the messaging systems, has, according to the NYT, caused much "internal strife".
His increased interference in the businesses is reported to be behind the resignation of Instagram’s founders, Kevin Systrom and Mike Krieger and WhatsApp’s founders, Jan Koum and Brian Acton.
There remain many questions over privacy - WhatsApp for example only requires users to register a phone number while Facebook demands you provide your identity.
Facebook have not yet addressed these issues, simply stating that: “As you would expect, there is a lot of discussion and debate as we begin the long process of figuring out all the details of how this will work."
Social media consultant Matt Navarra said."It might please those who don't like having to switch between multiple messaging apps to contact friends."
"This would seemingly make it possible to ping friends on WhatsApp from inside Messenger, for example.
"This helps Facebook compete with one of the biggest rival platforms for messaging, Apple's iMessage.
"With separate apps that are not integrated, users have to have connections in the same messaging app to connect with them and chat.
"iMessage has the broader capability of only being limited by users needing to have an Apple device. This Facebook change could address this limitation."