The European Union has proposed hefty fines on Google, Facebook, Twitter and other online platforms if they fail to remove extremist content within one hour.

“One hour is the decisive time window in which the greatest damage takes place,” Jean-Claude Juncker said in his annual State of the Union address to the European Parliament.

If authorities flag it, the European Commission wants content inciting or advocating extremist offences, promoting extremist groups, or showing how to commit such acts to be removed from the web within a hour.

In a proposal that will need backing from EU countries and the European Parliament, internet platforms will also be required to take proactive measures, such as developing new tools to weed out abuse and human oversight of content.

Service providers will have to provide annual transparency reports to show their efforts in tackling abuse. Providers systematically failing to remove extremist content could face hefty fines of up to 4 percent of annual global turnover. Content providers will have the right to challenge removal orders.