NEW YORK (NYTIMES) - A bipartisan group of state attorneys-general said on Thursday (Nov 18) that they had opened an investigation into Meta, the company formerly known as Facebook, for promoting its social media app Instagram while knowing of mental and emotional harms caused by the service.

At least nine states are involved in the investigation, including California, Florida, Kentucky, Massachusetts, Nebraska, New Jersey, New York, Tennessee and Vermont.

Massachusetts Attorney-General Maura Healey, a leader of the investigation, said the states were examining whether the company's actions violated consumer protection laws and put the public at risk.

"Facebook, now Meta, has failed to protect young people on its platforms and instead chose to ignore or, in some cases, double down on known manipulations that pose a real threat to physical and mental health - exploiting children in the interest of profit," Ms Healey said.

The move comes after a trove of documents from a former employee detailed research inside the social media company that suggested teenagers suffered body image issues when using Instagram.

The documents, called The Facebook Papers, were shared with journalists in October. The Wall Street Journal first reported on the documents and the issues at Instagram with the help of whistle-blower Frances Haugen.

Nebraska Attorney-General Doug Peterson, another leader of the investigation, said the states would examine the "the techniques utilised by Meta to increase the frequency and duration of engagement by young users and the resulting harms caused by such extended engagement".

"When social media platforms treat our kids as mere commodities to manipulate for longer screen time engagement and data extraction, it becomes imperative for state attorneys-general to engage our investigative authority under our consumer protection laws," Mr Peterson said in a tweet.

The states' investigation adds to building regulatory pressure on Meta and other giants of Silicon Valley.

Ms Haugen and public interest groups have filed at least nine complaints to the Securities and Exchange Commission claiming Meta misled investors about its efforts to protect users from disinformation and hate.

The Federal Trade Commission and dozens of states have filed antitrust lawsuits to break up Meta, and members of Congress have vowed to create privacy, speech and antitrust legislation aimed at reining in the power of Amazon, Apple, Facebook and Google.

Spanning tens of thousands of pages and gigabytes of data, The Facebook Papers show a company struggling to deal with many issues that come as a by-product of its enormous scale and billions of users, spanning topics like misinformation, addiction and manipulation of users around the world.

Much of the information came in the form of detailed reports investigating the issues, laid out by the company's research division.

Meta has said the research efforts are intended to address the issues they pinpoint, with the aim of improving the company's products and services.

The documents indicate that roughly one-third of teenage girls who already felt bad about their bodies said Instagram made them feel worse. "Comparisons on Instagram can change how young women view and describe themselves," the documents said.

Meta has disputed the characterisation of the initial reporting on Instagram's issues, saying that the story lacked context and left out vital information and was a poor interpretation of the data obtained by WSJ.

The company argued that on 11 of 12 well-being issues, the surveyed teenage girls said Instagram made them feel "better and not worse".

"It is simply not accurate that this research demonstrates Instagram is 'toxic' for teen girls," Ms Pratiti Raychoudhury, a vice-president and head of research at Facebook, said in a company blog post in September.

In a statement on Thursday, a representative for Meta strongly disputed the claims made by the state attorneys-general against Instagram.

"These accusations are false and demonstrate a deep misunderstanding of the facts," said Ms Liza Crenshaw, a spokesman for the company. "While challenges in protecting young people online impact the entire industry, we've led the industry in combating bullying and supporting people struggling with suicidal thoughts, self-injury and eating disorders."