Researchers at Cambridge University have found that seven social networking websites failed to delete photos from their servers even when a user asked for them to be removed, the BBC writes.

The team put photos on 16 different websites, noted the direct links where the images were stored, deleted them, and finally came back 30 days later to see what had happened. On seven of the sites, using the direct links, the Cambridge University researchers found that the images had, in fact, not been deleted. Facebook is one of these sites (MySpace, hi5, Bebo, LiveJournal, Xanga, and SkyRock also failed the test).

However, Flickr, Photobucket, and Fotki removed photos within one hour, and Blogger, Picasa and Orkut within 48 hours. The biggest surprise is Windows' Live Spaces, which removed photos instantly.

Photographers, you have been warned.