Facebook, Microsoft, Twitter and YouTube announced on Monday night that they are working together to build a database of photos and videos used to recruit people into terrorism.

The companies will create a shared database that identifies images via a unique digital fingerprint, making it easier for the platforms to identify and remove the imagery.

“There is no place for content that promotes terrorism on our hosted consumer services,” the companies said in a joint blog post.  “When alerted, we take swift action against this kind of content in accordance with our respective policies.”

Content flagged by the database will not be automatically removed from the platforms, the companies said. Instead, it will be reviewed by each company to determine whether it violates the company’s terms of service.

Social networks have faced criticism this year for doing too little to prevent their platforms for being used to spread terrorist propaganda.

The Telegraph reports it comes after MPs warned that social media sites were unwilling to crack down on terrorism because they feared it would “damage their brands” and that they were becoming the “vehicle of choice” for extremists.

The database will alert the websites’ staff when a version of the image or video is posted by a user, even if it hasn’t been posted before on the site itself. For example, if a terrorist Twitter account posts an extremist picture, Twitter’s moderators would report it to the database, and staff at Facebook would then be alerted if the same picture was posted on Facebook.

The technique is already used by companies to combat accounts sharing images of child sexual exploitation. It is believed to be especially effective on less public networks such as Facebook, where there is less chance of a user reporting a post.