A bug has been discovered which allows Facebook access to users' iPhone cameras as they scroll through the app.
The social network confirmed they were aware of the issue, and would be submitting a software fix to Apple.
A number of videos have been posted to Twitter by concerned Facebook app users, showing their phone cameras opening in the background when they clicked on a photo.
One social media user wrote: "Hey Facebook, can you explain why I can see my guitar through the camera of my iPhone that should not be active in the background while using your app? Alignment bug? Always watching?".
The bug appears to be limited to the version of the Facebook app available on Apple's iOS.
Responding to discussion of the bug, Facebook's vice president for integrity Guy Rosen, said there was "no evidence" of any photos or videos being stored to Facebook servers or being uploaded because of the flaw.
The social media giant said the bug was the result of an earlier software update to fix another bug found in its iOS app.
A spokeswoman for Facebook added: "We recently discovered that version 244 of the Facebook iOS app would incorrectly launch in landscape mode.
"In fixing that issue last week in v246 (launched on November 8) we inadvertently introduced a bug that caused the app to partially navigate to the camera screen adjacent to News Feed when users tapped on photos.
"We have seen no evidence of photos or videos being uploaded due to this bug. We're submitting the fix for this to Apple today."
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