More than 40 US states are suing Meta, the parent company of Facebook and Instagram, accusing it of profiting “from children's pain”, damaging their mental health and misleading people about the safety of its platforms.

"In seeking to maximize its financial gains, Meta has repeatedly misled the public about the substantial dangers of its Social Media Platforms," argued a joint lawsuit filed in a California federal court.

The legal filing alleges that Meta has exploited young users by creating features to maximise the time they spend on its platforms, despite harm to their health.

"Kids and teenagers are suffering from record levels of poor mental health and social media companies like Meta are to blame," said New York Attorney General Letitia James in a statement.

"Meta has profited from children's pain by intentionally designing its platforms with manipulative features that make children addicted to their platforms while lowering their self-esteem."

The lawsuit accuses Meta of deceptive and unlawful conduct harming vulnerable youth for financial gain, urging the federal court to order the company to cease manipulative tactics and pay significant financial penalties along with restitution.

"Social media companies, including Meta, have contributed to a national youth mental health crisis and they must be held accountable," James said.

Meta expressed disappointment at the suit, arguing that states should work with social media companies to establish age-appropriate standards. Meta maintained that it has developed more than 30 tools in its apps to support teenage users, and made it easier for parents to "shape" online activity.

The legal action follows a nationwide investigation launched in November 2021 after Facebook whistleblower Frances Haugen leaked internal documents revealing concerns about user security.