Billionaire owner of platform formerly known as Twitter says anti-Semitism accusations have hurt company’s bottom line.

Musk late on Monday accused the United States-based Jewish organisation of making unfounded complaints against him and X that have scared away advertisers.

“To clear our platform’s name on the matter of anti-Semitism, it looks like we have no choice but to file a defamation lawsuit against the Anti-Defamation League … oh the irony!” Musk wrote on X.

“Based on what we’ve heard from advertisers, ADL seems to be responsible for most of our revenue loss,” he wrote, adding that the group “would potentially be on the hook for destroying half the value of the company, so roughly $22 billion”.

“Advertisers avoid controversy, so all that is needed for ADL to crush our US & European ad revenue is to make unfounded accusations,” he wrote in a long thread that started with a clarification that he favours free speech but is “against anti-Semitism of any kind”.

The ADL declined to comment on Musk’s legal threats but responded to the “BanTheADL” hashtag that has been trending on the website.

Musk, who bought Twitter last year and rebranded it as X, has come under fire for liking posts with the hashtag.

“It is profoundly disturbing that Elon Musk spent the weekend engaging with a highly toxic, anti-Semitic campaign on his platform,” ADL chief executive Jonathan Greenblatt said in an email to the AFP news agency.

“This behaviour is not just alarming nor reckless, it is flat out dangerous and deeply irresponsible.”

The hateful campaign started after the ADL participated in a civil rights march marking the 60th anniversary of Martin Luther King’s “I have a dream” speech, according to the group.

The ADL has for years accused the social media site of amplifying anti-Semitic hate speech and recently met top executives at X.

In a 2016 report, the group said anti-Semitic attacks against journalists had exploded on Twitter, “thanks to the rhetoric in the 2016 presidential campaign”.

It accused the social network of failing to control its “trolling problem”.

Billionaire Musk has previously also been accused of fuelling anti-Semitic tropes, including attacks against Jewish philanthropist George Soros.

According to the ADL and the Center for Countering Digital Hate (CCDH), problematic and racist speech has sharply risen on X since Musk completed his $44bn takeover in October.

Since then, the Tesla boss has fired thousands of the platform’s employees, cut content moderation and reinstated former President Donald Trump’s account.

Last month, Musk sued the CCDH, accusing it of a smear campaign that damaged the social network’s relationship with advertisers.