The software glitch meant that third-party app developers may have been able to access “a broader set of photos than usual” during a 12-day period in September, according to the social media giant.

Facebook said in a blog post: “When someone gives permission for an app to access their photos on Facebook, we usually only grant the app access to photos people share on their timeline. In this case, the bug potentially gave developers access to other photos.”

Third-parties were potentially able to access photos shared on Marketplace or Facebook stories, as well as photos users had uploaded to the platform but subsequently decided not to post.

Facebook apologised for the error, saying it is working with developers to “delete the photos from impacted users”.

The company said it would inform users who had potentially been affected.