Elon Musk privately visited Auschwitz-Birkenau, the site of a former Nazi concentration camp, as the X owner defended his record on anti-Semitism.
Mr Musk laid a wreath and took part in a short memorial service alongside conservative US journalist Ben Shapiro and Holocaust survivor Gidon Lev.
He later appeared at a conference in the southern Polish city of Krakow, which addressed the rise in anti-Semitism since the Israel-Hamas conflict started in October.
The X platform has come under fire in recent months and has seen some major advertisers pause their spending since last year. In late 2023 Mr Musk publicly agreed with an X user who espoused an anti-Semitic conspiracy theory.
Mr Musk said on Monday that free speech was still the social media platform's general bias and that falsehoods being pushed should be corrected.
"The outside audits that we have had done ... show that there is the least amount of anti-Semitism on X, if you look at all the other social apps," he said as he was interviewed on stage by Mr Shapiro.
Mr Musk did not say who performed the audit or share any details from the report. He did not answer any questions from other journalists.
The Krakow event, organised by the European Jewish Association (EJA), focused on the "disconcerting surge of anti-Semitism in Europe" since the start of war between Israel and Hamas in October.
When asked about balancing free speech and tackling hate speech, Mr Musk said the platform favoured free speech.
"I think at end of the day free speech wins, in that if somebody says something that is false, especially on our platform, you can then reply to it with a correction," he said.
"So if somebody tries to push a falsehood, like Holocaust denial, they can immediately be corrected. And you can't get rid of the tag."
Mr Musk travelled to Israel in November where he met with leaders including Prime Minister Benjamin Netanyahu and President Isaac Herzog, and saw the sites where 1,200 people were murdered by Hamas on October 7.
