Iran is to expand what it calls "smart filtering" of the Internet, a policy of censoring undesirable content on websites without banning them completely, as it used to, the government said on Friday. The Islamic Republic has some of the strictest controls on Internet access in the world, but its blocks on U.S.-based social media such as Facebook, Twitter and YouTube are routinely bypassed by tech-savvy Iranians using virtual private networks (VPNs). Under the new scheme, Tehran could lift its blanket ban on those sites and, instead, filter their content.