The new service will mean the encrypted messages can only be read on one device of the person being messaged.

The company said that the development was in response to user demand for “additional safeguards… when discussing private information”. Whether a message is secret or not is optional, and within secret conversations, users will be able to set the amount of time a message sent remains visible within the conversation. But they will not support the use of rich content such as GIFs and videos.

In its statement, Facebook said: “We put people first in everything we do at Messenger, and today we are beginning to roll out a new option within Messenger to better support conversations about sensitive topics.”

During the test period, it will gather feedback on the functionality and performance. It said: “We are putting a lot of thought into the design and implementation of this feature, and we are grateful to the security and privacy experts who have given us their valuable input.”