But some child safety charities and experts have cast doubt on the effectiveness or promise of a midnight curfew for older UK teens.

"While we welcome these measures for older teens, this latest move is yet another piecemeal set of announcements, not the comprehensive plan for children's safety that's required," said Andy Burrows, chief executive of the Molly Rose Foundation.

He added that Prime Minister Sir Keir Starmer "leaves office having announced a social media ban without a plan" - with his likely successor Andy Burnham to "inherit a series of missed opportunities".

Prof Sonia Livingstone, an expert in children's digital rights at the London School of Economics, said a curfew could harm vulnerable children by limiting their access to social media when they might need it most.

"If it's a curfew on companies using push notifications to wake someone up in the night, absolutely have a curfew," Prof Livingstone told the BBC.

"But if it's a curfew that prevents a child in need of support or help or comfort reaching out to trusted sources in the middle of the night, I think that's quite harmful potentially."

Dame Rachel de Souza, children's commissioner for England, said: "We have to listen to young people. They don't want a ban, but they do want to be protected from addictive, infinite scrolling."

She added: "I want to know more about how the policies, such as a curfew, will be delivered and will be watching closely to make sure they are effective – alongside pushing Ofcom to make full use of its powers to make the online world safer for children."

Meanwhile, social media analyst Matt Navarra said the measure was "not a curfew" but a "mildly annoying settings prompt with a government press release attached".

"The UK Government is calling this 'world-leading' online safety, but with no VPN restrictions, it's leaving the side door open and putting up a sign asking teens not to use it," he said.