The Anne Frank Center has demanded that President Donald Trump fire White House Press Secretary Sean Spicer for saying in a news conference Tuesday that Adolf Hitler never used chemical weapons.

Spicer’s comment, delivered on the Jewish holiday of Passover, drew immediate widespread condemnation, including from Chelsea Clinton who suggested Spicer visit Washington D.C.’s U.S Holocaust Memorial Museum.

“On Passover no less, Sean Spicer has engaged in Holocaust denial, the most offensive form of fake news imaginable, by denying Hitler gassed million of Jews to death,” the center’s executive director, Steven Goldstein, said in a statement. “Spicer’s statement is the most evil slur upon a group of people we have ever heard from a White House press secretary, and President Trump must fire him at once.”

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“In no way was I trying to lessen the horrendous nature of the Holocaust,” Spicer later clarified. “I was trying to draw a distinction of the tactic of using airplanes to drop chemical weapons on population centers. Any attack on innocent people is reprehensible and inexcusable.”

Spicer’s comments were a botched attempt to defend Trump’s Syria policy by citing Syrian President Bashar al-Assad’s use of chemical weapons, and then claiming that “even” Adolf Hitler never used them.

“Hitler didn’t even sink to the level of using chemical weapons,” Spicer said.

Nazi Germany systematically killed millions of people in gas chambers at death camps during World War II, most notably at Auschwitz, where the gas of choice was Zyklon B, a form of hydrogen cyanide.

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Moments later, the White House Press Secretary attempted to clarify his factually inaccurate remark but only dug the hole deeper. Hitler, Spicer claimed, was “not using the gas on his own people in the same way that Assad is doing.”

But his words did little to quell anger on social media. As of this article’s publication, Sean Spicer was the top trending topic on Twitter.

This isn’t the first White House Holocaust gaffe. In January, the Trump administration came under fire for its statement on Holocaust Remembrance Day, which omitted any mention of Jews or anti-Semitism.

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