The Anne Frank Center blasted Sean Spicer on Tuesday, calling for his termination hours after the White House press secretary claimed that Adolf Hitler never used chemical weapons during World War II.

"On Passover no less, Sean Spicer has engaged in Holocaust denial, the most offensive form of fake news imaginable, by denying [that] Hitler gassed millions of Jews to death," Steve Goldstein, the center's executive director, posted on the group's Facebook page.

"Spicer's statement is the most evil slur upon a group of people we have ever heard from a White House press secretary," he continued.

The top Trump spokesman has faced an onslaught of criticism for referencing Hitler while discussing the recent chemical attack in Syria by the Assad regime.

"You had someone as despicable as Hitler, who didn't even sink to using chemical weapons," Spicer said of Syrian President Bashar Assad during Tuesday's White House briefing.

He later clarified that "when it comes to sarin gas, [Hitler] was not using the gas on his own people the same was Assad is doing."

Spicer then released a second statement shortly after the briefing in which he claimed he was "in no way trying to lessen the horrendous nature of the Holocaust."

"President Trump must fire him at once," Goldstein said.