Social media companies must do more to tackle extremism and terror, senior ministers have said in the wake of the Westminster attack.
Writing in the Sunday Telegraph, Home Secretary Amber Rudd said she was asking companies like Google, Twitter and Facebook to be more “proactive”.
She is due to meet the firms this week.
In the Sunday Times, Foreign Secretary Boris Johnson also called for internet companies to develop technology to detect and remove extreme material.
The calls come after Wednesday’s terror attack when attacker Khalid Masood ran down pedestrians and fatally a stabbed police officer who was guarding the houses of Parliament.
In total five people died – including the attacker who was shot by police – and 50 others were injured, two seriously.
On Saturday the Metropolitan police said they believed Masood acted alone. But they added they were also “determined” to find out whether he had been was inspired by terrorist propaganda.
Ms Rudd said: “Each attack confirms again the role that the internet is playing in serving as a conduit, inciting and inspiring violence, and spreading extremist ideology of all kinds…
“We need the help of social media companies, the Googles, the Twitters, the Facebooks of this world.
“And the smaller ones, too: platforms such as Telegram, WordPress and Justpaste.it.
“We need them to take a more proactive and leading role in tackling the terrorist abuse of their platforms.
“We need them to develop further technology solutions.”
Mr Johnson attacked internet giants for their “disgusting” failure to remove extremist material.
He said: “They are not acting when they are tipped off.
“Evil flourishes when good men do nothing – and that’s what’s happening here.
“They are putting up adverts next to it.”
Earlier this month, Google’s European boss apologised after adverts from major firms and government agencies appeared next to extremist content on its YouTube site.
Matthew Brittin promised to review the firm’s policies and strengthen enforcement.
Marks and Spencer and Audi were among the companies that pulled their online adverts over the issue.