Facebook, Google, Twitter and other technology giants must “live up to their social responsibilities” and do more to take down extremist material from the internet, David Cameron has suggested.
Mr Cameron said that the internet cannot remain an “ungoverned space” and that technology companies must be “more proactive” in helping authorities remove “harmful” material.
His intervention came after Robert Hannigan, the new head of GCHQ, warned last month that Facebook and Twitter have become “command and control centres” for Isil terrorists.
The security services are increasingly concerned that jihadists are exploiting social networking websites to spread their propaganda.
Meanwhile, the Metropolitan Police is currently taking down one terrorist-related posting every ten minutes from the internet, equivalent to 5,000 a week.
Mr Cameron disclosed that after negotiations lead by Downing Street, internet service providers including Virgin, Sky, BT and Talk Talk have agreed to incorporate a button enabling the public to report extremist material on their websites.
They have also agreed to ensure that their child protection filters protect young people from being exposed to jihadist material online.
However, Mr Cameron indicated that he wants to see major technology companies go further.
In his address to the Australian Parliament ahead of the G20 summit, Mr Cameron said: "A new and pressing challenge is getting extremist material taken down from the internet. There is a role for government in that. We must not allow the internet to be an ungoverned space.
"But there is a role for companies too. In the UK we are pushing companies to do more, including strengthening filters, improving reporting mechanisms and being more proactive in taking down this harmful material.
"We are making progress but there is further to go. This is their social responsibility. And we expect them to live up to it."
The Metropolitan Police is host to a counter terrorism unit dedicated to identifying and removing extreme graphic material from the internet.
In an average week the unit removes over 1,000 pieces of content that breach the terrorism act, 800 of which are related to Islamic State in Syria and Iraq.