Extremist images

Extremist images 'fingerprinted' by tech firms

The four tech firms plan to create a database that contains "digital fingerprints" of the content.

The database will be used to screen uploads in order to spot violent or extremist material before it is shared.

Eventually, the database will be made available to other firms keen to police this content.

"There is no place for content that promotes terrorism on our hosted consumer services," said a spokesman for Twitter in a statement.

He said the initiative was aimed at the "most extreme and egregious" images and videos.