The European Commission has urged the likes of Google, Facebook and Twitter to do more to remove extremist content - or face further regulation.
EU home affairs commissioner Dimitris Avramopoulos warned "the real battlefield is against 21st century terrorism".
He said most of the recent terrorist attackers had never travelled to Syria or Iraq. "But most of them had been influenced, groomed and recruited to terrorism on the internet."
Avramopoulos said he believed it was feasible to reduce the time it takes to remove content to a few hours. “There is a lot of room for improvement, for this cooperation to produce even better results, starting with the reporting from the companies, which must become more regular and more transparent.”
Avramopoulos also said he thought it was worthwhile to harness artificial intelligence to complete the task. He said: "Facebook, Twitter, YouTube: I urge you to work with smaller companies and help them set up their own Artificial Intelligence tools to detect terrorist content automatically."
The Commission said it would make a decision by May next year on whether additional measures – including legislation – are required in order to better address the problem of illegal content on the internet.
In June, Microsoft, Facebook, Twitter and YouTube formed a working group to combine their efforts in removing extremist content, forming a database which now contains more than 40,000 hashes of images and videos.
Facebook reports that it is now at 99 per automated removals, Google/Youtube at 98 per cent and Twitter at 95 per cent.
In his concluding remarks at the Internet Forum in Brussels, he told delegates: "It is important to remember why we are here today. The 38 jihadist attacks that struck the EU since August 2015 were not all due to online terror content. But internet propaganda has been the main push factor, inciting people to commit attacks, and instructing them how to do so.
"This is corporate social responsibility for the digital age. I hope we can see your engagement and cooperation continue and develop over the months to come." ®