The Conservatives have said they would ban social media for children under the age of 16.
Tory leader Kemi Badenoch said her party would raise the "age of consent" to "protect children" from harmful content such as extreme pornography.
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The policy goes a step further than the Tories' previous calls for smartphones to be banned in schools - a position the government has rejected on the grounds that it believes it is for individual schools to stop them being used in classrooms and that most do this anyway.
The Conservatives have said the ban is necessary in light of evidence showing that children are now spending record amounts of time online and are frequently being exposed to violent content, pornography and other extreme material, as well as potentially coming into contact with predatory or exploitative adults.
Ms Badenoch said: "As a mum, I know parents are under real pressure online.
"Our policy is simple: clear rules for children, but freedom for grown-ups. This is not about censoring adults or demonising social media companies, it's about helping people to take responsibility.
"Government's role isn't to police speech or tell adults what to think, but it should draw clear, enforceable lines to protect children. A simple age limit for social media does that. It protects kids properly and stops adults being treated like children.
"Our policy draws a clear line for under-16s, while protecting free choice and free speech for adults. Now the government must act."
It comes after Sky News reported how an 18-year-old has been living with PTSD after seeing a recording of a live video of a man taking his own life with a gun.
Social media platform X, owned by tech billionaire Elon Musk, has also faced criticism this week after numerous users, mainly women, posted saying they had seen AI-generated sexual images of themselves on X through the tool Grok.
X has said it takes action against illegal content, including child sexual abuse material, "by removing it, permanently suspending accounts, and working with local governments and law enforcement as necessary".
It then limited image editing on Grok to paid subscribers - but the changes were described as "insulting" by Downing Street.
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Under the Tories' policy, platforms such as TikTok and Snapchat would be required to ensure they are using age-verification methods that would not rely on any form of government digital ID - for example through parental verification, biometric facial analysis, passport confirmation or other methods.
The Conservatives have pointed to action taken by other countries including Australia, which has raised the age limit to 16 for social media use, while Malaysia has said it will do the same.
Denmark, France, Norway, New Zealand, Canada and Greece are also considering imposing restrictions.
Jane Rowland, co-founder of SafeScreens said: "For too long, the social media companies have had unrestricted access to our children's lives.
"The core purpose of these profit-driven platforms is to monopolise attention and monetise data, and as such they will never be benign places for children to spend time. This bold initiative marks a turning of the tide against social media's exploitation of children and their data."
Sky News has approached Downing Street for comment.
:: Anyone feeling emotionally distressed or suicidal can call Samaritans for help on 116 123 or email jo@samaritans.org in the UK. In the US, call the Samaritans branch in your area or 1 (800) 273-TALK
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