MPs are suggesting that advertisers boycott tech companies like Facebook and Google until they do more to tackle terrorism.
Social media companies and image hosting firms have been under considerable pressure to remove content from their sites. YouTube was criticized for videos that gave instructions about how to make a bomb from ingredients bought on Amazon.
Dominic Grieve, chairman of the intelligence committee, described it as a "matter of scandal" and urged businesses to put pressure on communications service providers in order to cut profits for Facebook, Google and others.
The Conservative party, of which Grieve is a member, spent a reported £2.1 million on Facebook ads in the run up to the 2017 general election.
Tech companies have acknowledged that more needs to be done. In 2017 Google announced it would hire 10,000 staff to monitor YouTube for unsuitable content.
Technology itself can help with this too, with YouTube claiming automated tools are able to flag 98 per cent of violent extremism for review. The company also claimed half of those videos are removed before 10 people see them.
There's also a list of 40,000 digital fingerprints used to detect commonly recurring extremist content. These are the product of cross-platform cooperation and prevent the same videos being posted on many sites.
Facebook says it is able to remove 99 per cent of Islamic State or Al Qaeda material before a user flagged it to the company. And Twitter says it can detect 93 per cent of extremist content with automated tools.
However, the BBC reports that MI5 has admitted to being too slow when dealing with terrorists. The Manchester Arena bomber was well known to the intelligence services before his attack which killed 22 and seriously injured 112 others.
Terrorists in the London Bridge, Westminster and Parsons Green attacks were all known, but no action was taken.