Twitter, or now known as X, has threatened to sue a group of independent researchers whose studies have documented an increase in hate speech on the platform since it was acquired by Elon Musk last year, AlJazeera reports.

An attorney representing X sent a notice on July 20 to the Center for Combating Digital Hate (CCDH) threatening legal action over the nonprofit’s research on hate speech and content moderation.

The letter claims that its findings appear to be intended “to harm Twitter’s business by driving advertisers away from the platform with inflammatory claims.”

The Centre, which has offices in the United States and the United Kingdom, regularly publishes reports on hate speech and harmful behavior on social media platforms such as X, TikTok and Facebook.

The organization has also published several reports critical of Musk’s leadership, detailing the increase in anti-LGBTQ hate speech and climate misinformation since his purchase.

The letter that X’s lawyer sent points to a June report that said the platform failed to remove neo-Nazi and anti-LGBTQ content from verified users who violated the platform’s rules.

Musk’s original promise was that he would allow free speech on his platform that wasn’t even illegal.

“I hope that even my worst critics remain on Twitter because that is what free speech means,” Musk wrote in a tweet last year.

X’s recent threat of a lawsuit raised the concern of the U.S. Representative Adam Schiff, a California Democrat, who said the billionaire was trying to use the threat of a lawsuit to punish a nonprofit group that is trying to hold the powerful social media platform accountable.