Image source, Getty Images
Elon Musk's social media platform X has sued a left-leaning pressure group that accused the site of allowing antisemitic posts next to advertising.
X's lawsuit alleges that Media Matters for America "manipulated" data in an attempt to "destroy" the platform formerly known as Twitter.
Firms including Apple, Disney, IBM and Comcast have paused adverts on X since the watchdog released its analysis.
After Mr Musk threatened the lawsuit, Media Matters called him a bully.
The advocacy group said last week that ads had appeared on X alongside posts supporting Nazism, such as Hitler quotes and Holocaust denial.
Separately, Mr Musk himself last week was accused of amplifying an antisemitic trope on the platform.
The lawsuit, filed in Texas on Monday, argues: "Media Matters knowingly and maliciously manufactured side-by-side images depicting advertisers' posts on X Corp's social media platform beside Neo-Nazi and white-nationalist fringe content and then portrayed these manufactured images as if they were what typical X users experience on the platform.
"Media Matters designed both these images and its resulting media strategy to drive advertisers from the platform and destroy X Corp."
Image source, Getty ImagesImage caption,
X chief executive Linda Yaccarino condemned the Media Matters report
X said in the lawsuit that ads for Comcast, Oracle and IBM had only appeared alongside hateful content for Media Matters, and no other viewer.
Linda Yaccarino, chief executive of X, posted on Monday: "Here's the truth. Not a single authentic user on X saw IBM's, Comcast's, or Oracle's ads next to the content in Media Matters' article."
In the wake of the Media Matters allegations, the European Commission, Warner Bros Discovery, Paramount and Lionsgate have also pulled ad dollars from X.
On Saturday, Mr Musk vowed to file a "thermonuclear" lawsuit against Media Matters, and anyone "who colluded in this fraudulent attack on our company".
In response, Media Matters president Angelo Carusone said they would win any legal action.
"Far from the free speech advocate he claims to be, Musk is a bully who threatens meritless lawsuits in an attempt to silence reporting that he even confirmed is accurate," Mr Carusone said in a statement.
Founded in 2004, Media Matters is known for its criticism of conservative commentators and media outlets.
It describes itself as a non-profit "progressive research and information center dedicated to comprehensively monitoring, analyzing, and correcting conservative misinformation in the US media".
Last Wednesday, Mr Musk came under fire after he replied to a post sharing a conspiracy theory accusing Jewish communities of pushing hatred against white people, calling it "actual truth".
The billionaire Tesla and SpaceX entrepreneur later denied antisemitism, saying his comments referred not to all Jewish people, but to groups like the Anti-Defamation League, a Jewish anti-hate monitor.
Watch: In August X took down flashing sign after complaints
Meanwhile, Texas Republican Attorney General Ken Paxton said on Monday that he had opened an investigation into Media Matters "for potential fraudulent activity" over its allegations about X.
His office released a statement calling the liberal group a "radical anti-free speech organization".
Mr Paxton also vowed to ensure that "the public has not been deceived by the schemes of radical left-wing organizations who would like nothing more than to limit freedom by reducing participation in the public square".
Also on Monday the White House announced President Joe Biden would join Threads - the Meta-owned rival to X.
Threads accounts have also been created for the president, first lady, vice-president and second gentleman.