Meta has agreed to pay up to $18 billion over 10 years to settle claims brought by 29 US states that its Facebook and Instagram platforms harmed children.

The settlement also requires Meta to introduce new safety measures for teenage users, including daily usage limits and overnight blocks, with the changes expected to be rolled out within months.

The agreement brings an end to a major federal trial in California, although Judge Yvonne Gonzalez Rogers has not yet formally approved the deal. She said on Wednesday that she was “inclined to grant it” and suspended the trial while she reviews the terms.

The lawsuit, filed in 2023, accused Meta of violating federal and state laws and contributing to harms affecting children through its platforms. Meta has consistently denied wrongdoing.

Under the agreement, the settlement money will be used by states for youth online safety initiatives and other priorities.

The total amount could reach $18 billion, although 30% of the payment is conditional on YouTube and TikTok implementing similar child-safety measures.

California Attorney General Rob Bonta said the settlement secured changes that could otherwise have taken years to achieve through litigation and appeals.

“Instead of getting tied up in years of trials and appeals, we have secured the changes we were after,” Mr Bonta said.

He added that most of the agreed changes would be implemented “within months”.

The settlement covers 48 states, the District of Columbia and three US territories, with 51 states and territories agreeing to a combined settlement worth about $17.1 billion. Texas reached a separate agreement valued at about $1 billion.

New Mexico has opted to continue with litigation, while Florida has also rejected the settlement.

The agreement has drawn criticism from Meta whistleblower Kelly Stonelake, who said the company should not have needed litigation to implement measures aimed at protecting children.

“Meta spent years insisting that the people raising these concerns were wrong, that its products were safe, and that it could be trusted to police itself,” she said.

Experts have also cautioned that implementing the measures could prove difficult, particularly in accurately identifying teenage users.

Professor Alan Woodward of the University of Surrey said the proposed limits and overnight blocks were relatively easy to implement but warned that the system depended on age verification methods that remain imperfect.

Dr Holly Bear of the University of Oxford described the measures as an important first step but said they would not be sufficient on their own because young people use multiple social media platforms.

The settlement is expected to increase pressure on other major platforms, including TikTok, Snapchat and YouTube, to introduce similar safeguards for younger users.