In an op-ed published in The Washington Post Facebook chief Mark Zuckerberg says the responsibility for monitoring harmful content is too great for firms like his to handle alone. He calls for countries around the world to pass new laws in four areas: "harmful content, election integrity, privacy and data portability." The announcement comes two weeks after the New Zealand gunman used the site to livestream his attack on a mosque in Christchurch. Zuckerberg also details a new set of rules he would like to see introduced on tech companies.