The shifts comes as Google, Facebook and Twitter Inc face a backlash over the role they played in the U.S. presidential election by allowing the spread of false and often malicious information that might have swayed voters toward Republican candidate Donald Trump.
The issue has provoked a fierce debate within Facebook especially, with Chief Executive Mark Zuckerberg insisting twice in recent days that the site had no role in influencing the election.
Facebook’s steps are limited to its ad policies, and do not target fake news sites shared by users on their news feeds.
