The Home Office has unveiled a new computer programme which it says can accurately detect extremist propaganda online and remove it instantly.
It was announced by the Home Secretary, Amber Rudd, at a conference in California aimed at preventing the spread of such material.
Major US internet and social media companies have come under increasing pressure from governments to do more to stop extremists groups using their platforms to spread messages.
The 'Global Internet Forum to Counter Terrorism' was launched last year by Facebook, Microsoft, Twitter and YouTube, and also brings together several governments, including the US and UK.
Ms Rudd praised firms for their work but warned there is still more to do.
"I hope this new technology the Home Office has helped develop can support others to go further and faster.
"We know that automatic technology like this can heavily disrupt the terrorists' actions, as well as prevent people from ever being exposed to these horrific images."
Concerns over the availability of material such as execution videos, recruitment campaigns and bomb-making instructions on the internet intensified after a wave of attacks across Britain in 2017.
Andrew Parker, Head of MI5, said companies have an "ethical responsibility" to help confront the unprecedented threat, while Britain and France are exploring plans that could see platforms face fines if their efforts are not up to scratch.