Facebook, Microsoft, Twitter and YouTube are joining forces to improve their efforts to remove terrorist-related content from their online services, following pressure that tech companies might not be doing enough to deter extremists from using their platforms, according to Bloomberg.

The four companies said today that they are creating a shared database of the most severe terrorist videos and images that they have removed from their sites. The database, which will be hosted by Facebook, will store "hashes", a kind of unique digital fingerprint created by a cryptographic algorithm, for each piece of content.

All photo and video content being uploaded to the participating services will have its hash automatically checked against the database. If it matches a hash already stored there, the database will send the company to which the content has been uploaded a notification so that it can be manually reviewed for possible removal, Facebook said in a statement. "We hope this collaboration will lead to greater efficiency as we continue to enforce our policies to help curb the pressing global issue of terrorist content online," the company said.

Facebook, Microsoft, Twitter and Google’s YouTube have all been under pressure from Western governments for not doing enough to remove content related to terrorist groups and far-right organizations. Earlier this week, the European Commission warned the time is running out for such U.S. tech companies to prove they are serious about tackling hate speech or face further regulation. In Germany, the Justice Minister has threatened to file criminal charges against Facebook for failing to curb hate speech from neo-Nazi affiliated groups.

Facebook said that each company would independently decide which content would have its hashes stored in the database. It said this would not include all the content these sites remove for violating their terms of service, but a subset of the most egregious videos and images. It also said that because the database only stores the hash, and not the actual image or video, no personally identifiable information will be shared between the companies.