A coalition of US state officials announced Friday they had launched an antitrust investigation of Facebook to determine if the social media giant "has stifled competition and put users at risk."
New York state Attorney General Letitia James released a statement announcing the action on behalf of seven other states and the District of Columbia.
The move marks the first official US antitrust action against one of the so-called Big Tech companies -- although a landmark case had targeted Microsoft back in the 1990s.
"Even the largest social media platform in the world must follow the law and respect consumers," James said.
"We will use every investigative tool at our disposal to determine whether Facebook's actions may have endangered consumer data, reduced the quality of consumers' choices, or increased the price of advertising."
Joining the action were attorneys general of Colorado, Florida, Iowa, Nebraska, North Carolina, Ohio, Tennessee, according to James.
Earlier this year, the US Justice Department said it would launch a "review" of major online platforms to determine if they have stifled innovation or reduced competition.
It was not immediately clear if the states would be working in coordination with federal officials.
Facebook, by far the largest social network, in the past has claimed it is not a monopoly and that consumers have many choices for how to connect with people online.