Online safety campaigners have urged Keir Starmer to block under-16s from accessing social media apps that do not meet strict safety standards, instead of implementing a broader Australia-style ban.

The NSPCC, Molly Rose Foundation and Smartphone Free Childhood said tech platforms should not be allowed to offer “risky” features to teenagers such as infinite scrolling, disappearing messages and push notifications.

“We are asking you to act now to require tech platforms to meet strict safety standards to continue to offer their services to under-16s,” they wrote in a letter to the prime minister.

“We believe a binary debate between banning children from social media or not can oversimplify what is a complex issue. Instead, platforms’ continued ability to offer accounts and services to children should be made conditional on their ability to demonstrate that they are safe.”

In Australia, where access to apps including Instagram and TikTok is restricted for under-16s, age limitations are imposed if a service enables social interaction between two or more users, and if it allows users to post material. Instead, UK campaigners are calling for a system that limits access to platforms based on whether they are “safe” or not.

The letter was sent a week before the closing of a UK government consultation on new online safety measures, including a potential under-16 ban. The consultation is also seeking views on whether to restrict features such as livestreaming and location sharing. The government has already pledged to take some form of action as a result of the consultation.

The campaigners expect apps to be vetted before they can be accessed by under-16s. New features would also undergo safety checks before they are launched. The UK’s legal framework for social media regulation, the Online Safety Act, is overseen by the communications watchdog, Ofcom.

The letter seeks to unify campaigners’ positions on an under-16 ban. MRF and NSPCC have stopped short of calling for a formal age limit – arguing that it would represent a safety “cliff edge” for teenagers – while Smartphone Free Childhood has called for access to be restricted for under-16s, in line with its calls for similar limits on smartphones.

“What’s so significant about this moment is that organisations across civil society are aligning around a simple principle: access to our children should be treated as a privilege that must be earned, not an automatic right,” said Joe Ryrie, the director of Smartphone Free Childhood.

Andy Burrows, the chief executive of MRF, a charity established by the family of Molly Russell, a British teenager who took her own life after viewing harmful online content, said the government should ensure safe app design was a “precondition for tech firms to do business in the UK”. The letter was also signed by the Future of Technology Institute thinktank, the campaign group FlippGen and the People vs Big Tech coalition.

A government spokesperson said ministers shared the group’s determination to keep children safe online, and it was not a question of “whether we will act, but how”.