Signed by the Republican governor Spencer Cox, the measures grant parents full access to their kids’ accounts — including private messages. They also impose a curfew on use between between 10.30pm and 6.30am.

“We’re no longer willing to let social media companies continue to harm the mental health of our youth,” Mr Cox tweeted after signing the measures. “As leaders, and parents, we have a responsibility to protect our young people.”

The state is the first to restrict access to social media to minors. The bill, which comes into effect in March next year, requires firms to verify users are 18 when creating accounts.

Another bill signed by Mr Cox enables parents to sue social media companies for financial, physical or emotional harm and details fines for firms if they target under-18s with advertising.