Facebook temporarily blocked connections from the Tor network on Tuesday. Activists and political dissidents who use the Internet to communicate with the outside world in countries where doing so is a crime. Facebook resolved the Tor issues and said that a high volume of malicious activity across Tor exit nodes triggered Facebook’s automated malware detection system. The role that Tor and Facebook played in facilitating the dissemination of information under restrictive regimes cannot be underestimated. These voices will increase in number and volume. They cannot be ignored, says Mark Zuckerberg.
Source: https://thehackernews.com/2013/06/facebook-temporarily-blocked-access.html