WhatsApp is rolling out a feature that allows users to have photos or videos vanish after they are seen.
WhatsApp said the feature was aimed at "giving users even more control over their privacy".
However, the government is facing a legal challenge over the use of "self-destructing messages" on encrypted-messaging apps.
Transparency campaigners say it eliminates accountability and the public record.
WhatsApp has focused its marketing of the new feature on regular consumers, saying it could be used for throwaway yet personal photos - when trying on clothes in a shop and asking a partner how they looked, for example, or sending someone a password.
Much like vanishing messages on other apps such as Snapchat, however, it is possible for a user to take a screenshot or screen recording of the message when it is first opened - or to film one screen with another camera.
The photos will not be saved in a phone's gallery app
The media cannot be forwarded, saved, shared, or starred
It will expire if not opened within two weeks
WhatsApp introduced a disappearing-messages function in November.
It erases text messages for both the sender and recipient after seven days - and is one of the areas of concern for the legal challenge to the government.
UK law says information relating to "substantive discussions or decisions" need to be kept on record for the historical archive.