According to Facebook's Statement of Rights and Responsibilities:
you grant us a non-exclusive, transferable, sub-licensable, royalty-free, worldwide
license to use any IP content that you post on or in connection with Facebook
It looks like they're laying claim to not only the content that you're posting on Facebook but also content you link to. IANAL but I doubt that this would hold up in court.
The only licence you've granted is one to the link itself, not the link's target. Reading it any other way would suggest that by linking to google.com you'd be granting Facebook the same licence to Google's content, which is ridiculous.
The agreement further states:
This IP License ends when you delete your IP content or your account unless your
content has been shared with others, and they have not deleted it.
Given that the only shareable content posted on Facebook is the link, it's reasonable to argue that if you were to delete your account (or even just the link) then the licence would be terminated.
If someone else follows your link and posts the photos themselves then odds are they've breached both your local copyright act and Facebook's ToS. You could have Facebook remove the content but you'd have to take action against them directly if you wanted damages.