Facebook is rolling out “secret conversations” for Messenger, which it first began testing back in July.

These one-to-one conversations will be end-to-end encrypted and can only be read on one device. Users can choose to set a timer to control the length of time each message remains visible.

They can send text, pictures and stickers but group messages, gifs, videos, voice or video calling and payments are not supported.

Earlier in the year, Facebook-owned WhatsApp introduced end-to-end encryption for all data.

Last month, rival Google released messaging app Allo, which has an incognito mode, where messages will have end-to-end encryption. However it was criticised because the app will store all non-incognito messages by default. This is also true for Facebook’s secret conversations mode.

Offering encryption as an opt-in rather than a default feature may help Facebook avoid the issues that WhatsApp faced in Brazil, where a court demanded that it hand over certain data which it claims it does not have.

Meanwhile, all three apps use the Signal Protocol for encryption, developed by Open Whisper Systems.

American Civil Liberties Union said it is providing legal counsel to Open Whisper Systems after the US government demanded metadata from several Signal accounts.