WhatsApp is rolling out a feature that allows users to have photos or videos vanish after they are seen.
After the recipient opens the image for the first time, “view once” deletes it, without saving it to a phone.
WhatsApp said the feature was aimed at “giving users even more control over their privacy”.
However, child protection advocates have expressed concern that auto-vanishing messages could help cover up evidence of child sexual abuse.
The National Society for the Prevention of Cruelty to Children (NSPCC) is already at odds with WhatsApp’s parent company Facebook over the use of encrypted messaging.
Such encryption means police cannot see the messages “in transit” – only the sender and receiver can. But auto-deleting messages could mean that devices seized in police raids would no longer contain evidence either.