"It is unacceptable to repeat the hideous lie behind the most fatal act of Antisemitism in American history at any time, let alone one month after the deadliest day for the Jewish people since the Holocaust," White House spokesperson Andrew Bates said, responding to Musk's post on Wednesday and referring to Hamas' Oct. 7 attack on Israel.

Representatives for Musk or X could not immediately be reached for comment on the White House statement.

X earlier declined to comment on Musk's post, which endorsed a post that falsely claimed members of the Jewish community were stoking hatred against white people. X CEO Linda Yaccarino wrote on Thursday: "When it comes to this platform - X has also been extremely clear about our efforts to combat antisemitism and discrimination. There's no place for it anywhere in the world - it's ugly and wrong. Full stop."

IBM said on Thursday it had immediately suspended all advertising on X after a report found its ads were placed next to content promoting Adolf Hitler and the Nazi Party.

Advertisers have fled the site since Musk bought it in October 2022 and reduced content moderation, resulting in a sharp rise in hate speech on X, civil rights groups have said.

Antisemitism has been on the rise in recent years in the United States and worldwide. Following the outbreak of war between Israel and Palestinian Islamist group Hamas after last month's attack, antisemitic incidents in the United States rose by nearly 400% from the year-earlier period, according to the Anti-Defamation League, a nonprofit that fights antisemitism.

(Reporting By Jarrett Renshaw, Steve Holland and Sheila Deng; Writing by Susan Heavey; Editing by Daniel Wallis)