The Constitutional Council said the proposed age limit was not “suitable, necessary or proportionate” to the government’s aim of protecting children from pornography, abuse, bullying and isolation. It also objected to requiring all users to prove they were aged 15 or over.

The council, whose members are known as Les Sages (the Sages), often strikes down parts of bills – but it is rare for it to quash flagship legislation entirely.

The ruling is a setback for President Emmanuel Macron, who had hoped to introduce the ban next month after the bill was approved by both houses of parliament.

Mr Macron said Prime Minister Sébastien Lecornu would prepare a new version by spring, although commentators have questioned whether it can pass before Mr Macron’s presidency ends in May.

The French proposal would have banned under-15s from all social media, subject to limited exemptions. The council said this could prevent teenagers from accessing platforms where no health or safety risk had been established.

It also said parents should be able to exempt their children if they believed doing so was in their best interests.

Australia remains the only country to have introduced a nationwide social media ban, restricting under-16s from platforms including TikTok and Snapchat.