Keir Starmer has promised a “fight” with social media companies amid efforts to limit children’s use of mobile phones, tablets and TVs, as new official guidance recommends children under five spend no more than an hour a day on screens.

The guidance, developed by a panel led by the children’s commissioner, Rachel de Souza and children’s health expert Prof Russell Viner, advises screen time for children under two should be avoided other than for shared activities.

Ministers are also considering Australia-style measures to limit or ban social media for under-16s.

Speaking at a school in south London about the new guidance, the prime minister said: “When there’s a lot going on, when children are having a tantrum, trying to find something to distract them is an obvious thing, and I don’t think parents and carers have had any guidance at all yet about what would be appropriate, what might be best.”

The government is consulting on potential age restrictions on social media and other services, such as gaming sites and AI chatbots, as well as restrictions on addictive design features and risky functionalities, and better support for parents and families.

Starmer said: “Some of this will require a fight. If we’re going to do more to protect children, we’re going to have to fight some of the platforms that are putting the material up there because they’re putting this addictive stuff up there for a reason. They want more children to spend more time online and we’ve got to fight them and be clear whose side we’re on here.”

For the purpose of the guidance, screens include tablets, laptops, mobile phones and television.

It advises families of two- to five-year-olds to avoid fast-paced social media-style videos, and toys or tools that use artificial intelligence.

Bedtimes and mealtimes should be screen-free, with families advised to instead try background music, table games, bedtime stories and colouring.

Watching screens with children and talking and asking questions about the content was better for a child’s cognitive development than letting them use them alone, the guidance says.

Shared screen activities could include video calling friends and family or looking through photos together, it advised.

About 98% of children are watching screens on a daily basis by the age of two, the government has said previously.

Infants with the greatest amount of screen time are significantly less likely to regularly be read to or go on trips outside, the Education Policy Institute has found. There was also found to be an impact on their language development.

Viner, a professor in adolescent health at University College London, said: “Too much solo screen time can crowd out the things that make the biggest difference – sleep, play, physical activity and talking with parents and carers.”

The panel recommended in its report that parents should think about their own screen use in front of their children, and consider screen-free periods of the day for the whole family.

Dr Mike McKean, the vice-president for policy at the Royal College of Paediatrics and Child Health, welcomed the guidance to help parents protect “short, but developmentally crucial early years”.

“The growing emphasis on online and digital spaces has made childhood an even more challenging period for parents to navigate,” he said. “For many years now parents and professionals have been forced to play a dangerous game of catch up, desperately trying to find the right balance for their children.”

It is hoped the advice on screen time will help children and families have healthier relationships with screens, and use them in a way that does not risk impacting their readiness to start school.

Long periods of time spent on screens alone impacts activities that are key for good development, such as sleep, physical activity, creative play and interaction with parents, the panel found in its review of the evidence.

However, limits on screen time should not be applied in the same way for children with special educational needs and disabilities who used screen-based assistive technologies, the panel said.