Amber Rudd has urged tech giants in Silicon Valley to “unite” to stop terrorists from using their platforms to “weaponise vulnerable people in their homes.”
The Home Secretary told representatives of Facebook, Twitter, Microsoft and YouTube at a meeting in San Francisco on Tuesday that along with governments, they needed to do more to stop radicalisation online.
"Our enemy is trying to weaponise vulnerable people in their homes," she said.
"It is a war where the front line can be a screen in a young person's bedroom or the mobile phone in their pocket.
"We must be united in our resolve to purge the internet of this poisonous and pernicious material."
She credited the internet firms with "strides they are taking in making the internet a hostile place for terrorists to operate", but said the problem could not be tackled by any one of them alone.
"We need to do more to help keep our communities safe," she urged them.
The Home Secretary was attending the first meeting of the Global Internet Forum to Counter Terrorism - an initiative the firms set up in June to tackle radical content on their platforms.
Also present at the meeting was US acting secretary of homeland security, Elaine Duke, in one of her first official appearances in the role after John Kelly started as President Donald Trump's new chief of staff on Monday.
The internet firms say their forum will look at technical ways to combat online radicalisation and share its research with governments, academics and smaller companies.
Earlier this year, a committee of MPs accused social media firms of a "shameful" failure to tackle online terrorist propaganda and hate speech.
In June Metropolitan Police Assistant Commissioner Mark Rowley, the country's most senior counter-terror officer, urged internet-based companies to "show more responsibility".
Writing in The Times, he warned: "It is too easy for the angry, violent or vulnerable to access extremist views, learn about attack methodologies, conspire on encrypted applications and then acquire equipment to kill, all online."
Britain and France are looking at plans that could see technology firms face fines if their efforts to tackle terrorist material are not up to scratch.
The proposals - unveiled by Theresa May and French president Emmanuel Macron in June - include exploring the possibility of creating a new legal liability for companies if they fail to remove unacceptable content.
Additional reporting by Press Association.
