Ministers will take another step towards banning social media for under-16s next week as they launch a consultation on the policy, with government insiders increasingly certain Keir Starmer will back the idea.

Liz Kendall, the technology secretary, will publish the terms of reference for the consultation, which is expected to explore options including an age limit and less hardline action such as curbs on infinite scrolling.

Government insiders say the consultation will not back one option over another, but ministers and officials believe the prime minister will announce his support for a ban in the summer.

One senior government figure involved in drawing up the consultation said: “I am sceptical about whether a ban will work, but I am sure we will end up backing a ban, not least because that is the way the politics is heading. In a way it doesn’t necessarily matter whether it is universally adhered to or not – a ban is the clearest signal to the industry that we want them to do more to protect young people online.”

Another source added: “A ban is the simplest way to achieve what we want. Everything else is asking social media companies to redesign the way the platforms work and be open and transparent about it, which seems more complicated.”

A government spokesperson said: “Parents are deeply worried about the effects of social media on their children, and we’re determined to get this right. Our swift consultation will look at everything from age limits and safer design features to a social media ban.

“We are listening to a wide range of voices including parents, teachers, young people and experts to give young people the childhood they deserve and prepare them for the future. We will set out our plans in the summer based on the outcome of the consultation.”

Kendall announced the consultation last month under heavy pressure from Labour backbenchers, some campaigners and the Conservative party.

Starmer was initially sceptical of a ban, as were several senior ministers, saying they were concerned it would be easy to circumvent and leave teenagers ill-equipped to use social media when they reached age 16.

However, Australia’s move to enact a ban in December has galvanised supporters of the policy, who say the early results there show it could be rolled out successfully in the UK.

Fred Thomas, the Labour MP who organised a letter signed by more than 60 backbenchers calling on Starmer to back a ban, said: “Every day that goes by with children being harmed is one we will regret. We must help parents protect under-16s by removing their access to this addictive, dangerous content.

“Bold, confident action is required – and the plentiful evidence supports decisive intervention. Children, parents and politicians of all stripes recognise the corrosive damage it is causing our society.”

The consultation comes as Instagram announced that parents of teenage users would be alerted if their child repeatedly uses search terms associated with suicide or self-harm.

The social media platform, owned by Mark Zuckerberg’s Meta, said parents would be contacted via email, text or WhatsApp as well as Instagram notifications if their child had searched for specific terms repeatedly within a short period of time.

This will apply to parents in the UK, US, Australia and Canada who use Instagram’s parental supervision function, which is an extra set of controls that allows adults to regulate teenagers’ account settings.

The Molly Rose Foundation (MRF), a charity established by the family of Molly Russell, a British teenager who killed herself aged 14 after viewing harmful content on Instagram, said the platform should address its algorithm, which still recommends harmful depression, suicide and self-harm material to vulnerable young people.

“Every parent would want to know if their child is struggling, but these flimsy notifications will leave parents panicked and ill-prepared to have the sensitive and difficult conversations that will follow,” said Andy Burrows, the chief executive of MRF, which received a donation from Meta after the inquest into Molly’s death.

• In the UK, the youth suicide charity Papyrus can be contacted on 0800 068 4141 or email pat@papyrus-uk.org, and in the UK and Ireland Samaritans can be contacted on freephone 116 123, or email jo@samaritans.org or jo@samaritans.ie. In the US, the 988 Suicide & Crisis Lifeline is at 988 or chat for support. In Australia, the crisis support service Lifeline is 13 11 14. Other international helplines can be found at befrienders.org