A security researcher has found that WhatsApp isn't properly deleting messages

Security researcher Jonathan Zdziarski has discovered that WhatsApp doesn't fully delete messages when a user chooses to delete them through the app.

The Verge reports that Zdziarski examined the WhatsApp app to see what happened to messages after he chose to delete them. Instead of properly disappearing as they should do, they remained hidden inside the app.

This isn't about Facebook storing deleted messages on WhatsApp's servers - instead it's to do with the local storage on the app.

There's no suggestion that Facebook is retaining the messages on its own servers. Facebook did not reply to a request for comment on this story.

Zdziarski's findings mean that police or other people could access messages that a user thought had been deleted if they were able to unlock the iPhone or download an iCloud backup of the device and the WhatsApp app.