Kemi Badenoch has announced that the Conservatives would ban under-16s from using social media if they win power in the next election.
The Tory leader said the party would follow the example of Australia, which became the first country to introduce the ban last month.
Speaking to the BBC, she claimed the use of "addictive" social media apps "correlates quite strongly" with a surge in mental health problems.
She said: "We tell children what to do all the time. Children are not adults. Freedom is for adults.
"Adults should be able to cope with that and manage themselves. Children, we need to protect."
The ban would see social media companies, including TikTok and Snapchat, use age verification tools to prevent under-16s from using their platforms.
Her calls were backed by the Manchestor Mayer, Andy Burnham, saying he agreed with "a lot of what Kemi Badenoch is saying."