Today Google issued a “Disavow Links tool” which enables webmasters to take control of undesirable links and ask that they be disregarded for ranking purposes.

Webmasters who believe their site’s ranking is being harmed by low-quality links from spam sites can now take control and ask Google not to take them into account when assessing ranking.

The primary function of the ‘Disavow Links’ tool is to help clean up if you’ve hired a bad SEO or made link-building mistakes in the past”

“If you know of bad link-building done on your behalf (e.g., paid posts or paid links that pass PageRank), we recommend that you contact the sites that link to you and try to get links taken off the public web first,” advises Google. “You’re also helping to protect your site’s image, since people will no longer find spammy links and jump to conclusions about your website or business.”

“If you’re unable to get a few back-links taken down, should the ‘Disavow Links’ tool be used. However, if you disavow a link in error it could be some time before that link is reinstated, if ever, so caution is advised.”