Facebook said Friday it had taken down accounts linked to an Iranian effort to influence US and British politics with messages about charged topics such as immigration and race relations. The social network identified 82 pages, groups and accounts that originated in Iran and violated policy on coordinated "inauthentic" behavior, Facebook head of cybersecurity policy Nathaniel Gleicher said. Gleicher said there was overlap with accounts taken down earlier this year and linked to Iran state media, but the identity of the culprits had yet to be determined. "It's often hard to know who is behind this type of activity," Gleicher said in a telephone briefing.