Google, YouTube, Facebook, Twitter and other internet companies must show the European Union within three months that they are removing extremist content more rapidly or face legislation forcing them to do so.
Several governments have increased pressure on social media companies to do more to remove illegal content -- from material related to groups such as Islamic state and incitement to commit atrocities -- and the sector has increased efforts to demonstrate its progress.
But in its strongest call yet to the technology sector the European Commission on Thursday recommended measures that internet platforms should take to stop the proliferation of extremist content, including the removal of such material within an hour of being notified of its existence.