Internet companies have reiterated their commitment to help combat online extremism after Theresa May accused big tech firms of giving terrorist ideology "the safe space it needs to breed".
The prime minister levied the criticism as she reacted to the London terror attack and called for more to be done "to prevent the spread of extremist and terrorism planning".
Mrs May said: "We cannot allow this ideology the safe space it needs to breed".
She added: "Yet that is precisely what the internet, and the big companies that provide internet-based services provide.
In response,Facebook said it condemned recent attacks and wanted the social media platform to be "a hostile environment for terrorists".
In a statement, Simon Milner, director of policy at Facebook, said: "Using a combination of technology and human review, we work aggressively to remove terrorist content from our platform.
"As soon as we become aware of it - and if we become aware of an emergency involving imminent harm to someone's safety, we notify law enforcement."
Nick Pickles, UK head of public policy at Twitter, said: "Terrorist content has no place on Twitter.
"We continue to expand the use of technology as part of a systematic approach to removing this type of content.
"We will never stop working to stay one step ahead and will continue to engage with our partners across industry, government, civil society and academia."
Twitter also says it shut down 376,890 accounts linked to terrorism in the last six months of 2016.
Meanwhile, a Google spokesman said: "We are committed to working in partnership with the Government and NGOs to tackle these challenging and complex problems, and share the Government's commitment to ensuring terrorists do not have a voice online.
"We employ thousands of people and invest hundreds of millions of pounds to fight abuse on our platforms and ensure we are part of the solution to addressing these challenges."
The Tory manifesto has also called for a much tougher approach to regulation on the internet.
Proposals include tougher sanctions for companies that fail to remove illegal content, as well as legislating for an industry-wide levy on social media companies to counter harmful activity online.
Digital campaigners the Open Rights Group said it was disappointing Mrs May had focused on internet regulation and encryption in the aftermath of the London Bridge attack.
"This could be a very risky approach. If successful, Theresa May could push these vile networks into even darker corners of the web, where they will be even harder to observe.
"But we should not be distracted: the internet and companies like Facebook are not a cause of this hatred and violence, but tools that can be abused.
"While governments and companies should take sensible measures to stop abuse, attempts to control the internet is not the simple solution that Theresa May is claiming."
Professor Peter Neumann, director of the International Centre For The Study Of Radicalisation at King's College London, said:
"Few people radicalised exclusively online. Blaming social media platforms is politically convenient but intellectually lazy.
"In other words, May's statement may have sounded strong but contained very little that is actionable, different, or new."