Medical experts have been instructed to draw up official guidelines for social media use amid fears over its impact on child mental health, Matt Hancock has revealed.
The Health and Social Care Secretary said he was "very worried" as a father by the growing evidence of the detrimental effect on the health of young people.
He told the Observer he had instructed Dame Sally Davies, the UK's chief medical officer, to begin preparing official guidance on safe time limits that would work in a similar way to safe alcohol limits.
Speaking ahead of the start of the party conference in Birmingham, he told the newspaper: "I am, as a father, very worried about the growing evidence of the impact of social media on children's mental health.
"Unrestricted use (of social media) by younger children risks being very damaging to their mental health.
"So I have asked the chief medical officer to bring forward formal guidance on its use by children."
Some platforms, including Facebook and Instagram, have moved to mitigate fears of addiction by introducing wellbeing tools that enable users to monitor and restrict their time on the platform.
Public campaigns such as Scroll Free September have also been launched to encourage the public to use social media less.
The initiative from the Royal Society for Public Health (RSPH) asked people to stop using platforms such as Facebook, Instagram, Twitter and Snapchat in September, or to cut down the amount of time they spend on them.
Almost two-thirds of users polled in a July survey considered taking part in the initiative and many believed giving up social media would have a positive impact on their lives, an RSPH survey found.
Mr Hancock hit out at both platforms, which share an owner, over a lack of policing of their rules on age limits.
He told the Observer: "The terms of reference of Facebook and Instagram say you shouldn't be on it if you are under the age of 13. But they do nothing to police that.
"The guidelines for WhatsApp say you shouldn't be on it unless you're 16. But again, they don't lift a finger."
Bernardo's welcomed the announcement.
Chief executive Javed Khan said: "There is growing concern about the impact of unrestricted social media use on children and young people and their mental health.
"At the moment a child spends on average almost five-and-half hours per day on social media, which is almost as long as they spend at school.
"Barnardo's has been calling for guidance around screen time and social media use for some time and we welcome the government listening to the concerns of professionals and parents. Measures that take us a step closer to safer online experiences are vital in promoting online safety and well-being for children.
"This new guidance will be important in supporting parents and carers to enforce rules for children and young people about when their online time is up."
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