The memorial's account reported the offensive material, which referred to the mass murder by the Nazis as a "fairytale" and included an antisemitic meme, on Sunday.

Despite X, formerly Twitter, listing Holocaust denial as a breach of its policies, it initially told the museum there was nothing wrong with the post and it remained live.

The post had been removed as of Tuesday morning and the account, which only had 20 followers, was suspended.

The museum has since highlighted another account posting a Holocaust conspiracy theory.

The account, @MillerStream, has a verification tick and almost 100,000 followers.

X has not responded to numerous reports about the post, the museum said.

"This time we did not even get a reply," it added, tagging the accounts of Musk and X chief Linda Yaccarino.

Sky News has contacted X for comment.

Musk removes block feature

It comes after the Auschwitz Museum criticised Musk's decision to remove the block feature on X.

The move is the latest in a long line of controversial changes to the platform's content moderation stance since the billionaire took over last October.

He said the block feature "makes no sense" and would only remain in place for direct messaging.

The Auschwitz museum, which preserves the site of a former concentration camp in Poland where at least 1.1 million people, mostly Jews, were killed by the Nazis, was quick to oppose the change.

"Failing to address the antisemitic and Holocaust denial comments that appear under our posts commemorating the victims of Auschwitz would be a disservice to their memory," it said.

"We've chosen to block users who promote denial and hatred."

Read more:
Taliban backs Musk's content stance
Musk reveals reason for Twitter rebrand

'Free expression'

Musk, a self-described free speech absolutist, has repeatedly defended his stance on content moderation.

Earlier this month, X sued a hate speech watchdog that accused the world's richest man of overseeing a rise in abusive posts and disinformation.

The Center for Countering Digital Hate has reported an increase in hateful language, criticised the dropping of COVID misinformation policies, and the placement of adverts next to posts from controversial accounts.

The social media firm, renamed X last month, has said any policy changes are about protecting "free expression".