Mark Zuckerberg has issued a reminder – and an apparent warning – to Facebook Messenger users who are sniffing their chats.

The Facebook founder and CEO of parent company Meta said in a post Friday that an update to Messenger will notify users if an image of their chat has been captured by someone else.

“New update for end-to-end encrypted Messenger chats so you’ll get notified if someone captures a message that disappears,” Zuckerberg wrote along with a screenshot of a chat with his wife, Priscilla Chan.

“We are also adding GIFs, stickers and reactions to encrypted chats,” he added.

The announcement follows an update to the widely used Facebook Messenger platform that allows people to have their messages disappear.

The feature has so far rolled out in the US and is expected to be introduced for Facebook users in Europe in the coming weeks, according to USA today.

Competing messaging platforms already offer options to dismiss user messages, as well as notifications when a conversation has been captured.

This includes Snapchat, while messaging apps such as WhatsApp include end-to-end encryption – another recent new introduction to Facebook.

Reports suggest Facebook’s decision was in response to security concerns and a broader controversy around online safety and free speech rights.

“When do you add the dislike button? We need answers…,” one Facebook user wrote in response to Mr Zuckerberg’s post.

“Maybe he can figure out how to feed the hungry or better, cure all the mental illnesses caused by these platforms, or maybe house the homeless,” an apparent skeptic added of the update. Facebook Messenger. “Can he do any of these?”

The updates will also apply to Instagram, which is owned by Meta.