Washington - White House Press Secretary Sean Spicer said on Tuesday that Adolf Hitler "didn't even sink to using chemical weapons" - a comment at odds with Hitler's use of gas chambers to exterminate Jews during the Holocaust.Spicer was attempting to discuss the horror of the chemical weapons attack last week in Syria, which the Trump administration is blaming on President Bashar Assad."We didn't use chemical weapons in World War II," said Spicer, adding that "someone as despicable as Hitler... didn't even sink to using chemical weapons".Minutes later, Spicer delivered a garbled defence of his remarks in which he tried to differentiate between Hitler's actions and the gas attack on Syrian civilians last week. The attack in northern Syria left nearly 90 people dead, and Turkey's health minister said tests show sarin gas was used."I think when you come to sarin gas, there was no, he [Hitler] was not using the gas on his own people the same way that Assad is doing," Spicer said. "There was clearly ... I understand your point, thank you. There was not ... He brought them into the Holocaust centre I understand that.""I appreciate the clarification. That was not the intent," he said.After the briefing, Spicer emailed a statement to reporters: "In no way was I trying to lessen the horrendous nature of the Holocaust. I was trying to draw a distinction of the tactic of using airplanes to drop chemical weapons on population centres. Any attack on innocent people is reprehensible and inexcusable."Spicer's comments came on the first day of Passover and a day after the White House held a Seder dinner marking the emancipation of the Jewish people, a tradition started during the Obama administration.According to the US Holocaust Memorial Museum, the Nazis experimented with poison gas in late 1939 with the killing of mental patients, which was termed "euthanasia". Both mobile and stationary gas chambers were later used, with up to 6 000 Jews gassed each day at Auschwitz alone.It was the second day in a row in which Spicer appeared to have trouble articulating the President's foreign policy at a critical time.Barrel bombsOn Monday, the White House was forced to walk back remarks Spicer made from the podium that the use of barrel bombs by Assad's government might lead to further military action by the United States.In an exchange with reporters on Monday, Spicer appeared to draw a new red line for the Trump administration when he told reporters that if a country gases a baby or it puts "a barrel bomb into innocent people, I think you will see a response from this President".Until Monday the administration had maintained that last week's airstrikes were in response to the Syrian government's use of chemical weapons against its own citizens. A White House spokesperson said later that "nothing has changed in our posture" and the President retains the option to act if it's in the national interest.The comments about Hitler immediately reverberated through the Jewish community.Calls for Spicer's dismissalThe New York-based Anne Frank Centre for Mutual Respect called on Trump to fire Spicer, saying he denied that Hitler gassed Jews during the Holocaust. Steven Goldstein, the centre's executive director, said in a statement that "on Passover no less", Spicer had "engaged in Holocaust denial, the most offensive form of fake news imaginable, by denying Hitler gassed millions of Jews to death. Spicer's statement is the most evil slur upon a group of people we have ever heard from a White House press secretary."Jewish Democrats quickly denounced Spicer's comments. Senator Ben Cardin said on Twitter, "Someone get @PressSec a refresher history course on Hitler stat (hashtag)#Icantbelievehereallysaidthat."Senator Brian Schatz of Hawaii said on Twitter he found "nothing funny about the Press Secretary bungling holocaust history. Because I'm not sure they should get the benefit of the doubt".It's not the first time the Trump administration has been criticised for comments related to the Holocaust and anti-Semitism. The White House released a statement on international Holocaust Remembrance Day earlier this year that did not make any reference to Jews, and some have taken issue with the speed with which Trump has condemned anti-Semitic attacks, including threats against Jewish community centres.