Sir Keir Starmer will today complete another U-turn by banning under-16s from using social media.

He had previously opposed a crackdown on apps, believing it would be difficult to enforce.

He was forced to change tack after dozens of Labour MPs called for urgent action to protect the young, sparking fears he could lose a Commons vote.

Today he will announce the Government will stop under-16s using ten of the biggest social media platforms including TikTok, Instagram, YouTube and X.

Sir Keir's approach will go further than that introduced in Australia by stopping strangers contacting children in gaming apps and banning under-18s from using sexual chatbots.

There will also be curfews for 16 and 17-year-olds to stop addictive late-night scrolling – despite Labour viewing them mature enough to be given the vote.

But campaigners for stronger protection against harmful online content – such as Ian Russell, whose daughter Molly, 14, took her own life in 2017 – have said 'sledgehammer techniques like bans' would only cause more problems.

Sir Keir said last night: 'This is a choice about whose side we're on: families across the country, or a status quo that isn't working. People expect action and this Government will always stand up for parents and put children first.'

No 10 said 90 per cent of the more than 116,000 questioned in a recent Government consultation backed a minimum age of 16 for going on social media. 

The crackdown comes days after Sir Keir warned tech giants he will act unless they ban children from being able to take, view or share nude photos on mobile phones.

Culture Secretary Lisa Nandy said yesterday: 'The tech companies have had more than enough time to get their house in order.'

But critics accused Sir Keir, who could face a leadership challenge within weeks if Andy Burnham wins the Makerfield by-election on Thursday, of only acting to secure his legacy.

Shadow education secretary Laura Trott said: 'It's shameful that it's taken the Prime Minister's job to be on the line for the Government to finally U-turn and ban social media for under-16s.'

Tory Lord Nash, whose amendment to the Children's Wellbeing and Schools Bill, calling for an immediate ban was repeatedly passed by the Lords but voted down on Sir Keir's orders in the Commons, called for robust age verification to ensure enforcement of the ban.

But Andy Burrows, chief executive of the Molly Rose Foundation, set up in memory of Molly Russell, said: 'A social media ban leaves parents with a false sense of safety. A majority of children will continue to use high-risk sites that will have no incentive to implement robust protections.'

Mr Russell said Sir Keir should be enforcing laws already on the books more robustly, rather than imposing a ban rushed through for 'deplorable' political reasons.

There are also concerns the ban will create a digital ID system by the back door, if it means adults will also have to prove their age when using social media.

'This will be remembered as the beginning of ID checkpoints for the internet,' said Silkie Carlo, of the group Big Brother Watch.