Urgent - Multisite Privacy, images available via direct URL and appearing in google image search

I am using multisite privacy to protect several blogs, the setting is set to:

"Only registered users of this blogs can have access - anyone found under Users > All Users can have access"

However images are directly viewable to anonymous users via their direct URL and some are also appearing on google image searches.

I do not want to supply a URL to test via this semi-public forum so can we please communicate via email.

This is quite urgent.

Thanks
Jack