Social networking service Pinterest has responded to concerns over copyrighted material by allowing websites to opt-out of being featured on the site.
The site, which bills itself as a "virtual pinboard", allows users to post pictures and other content onto a personalised profile.
However, some have raised concerns that the format encourages unauthorised sharing.
Concerned sites can now block their content by adding a line of web code.
Any Pinterest user attempting to share images or other material from a site with the "nopin" instruction will be told: "This site doesn't allow pinning to Pinterest. Please contact the owner with any questions. Thanks for visiting!"