Sean Spicer apologises amid uproar over Holocaust remark

White House press secretary Sean Spicer has apologised over a controversial comment he made in relation to the Holocaust on Monday, as he faces calls to resign from his position.

Spicer said during a press conference on Tuesday that Adolf Hitler had never used chemical weapons, in a comparison with Syrian President Bashar al-Assad, who has been accused of using sarin gas on civilians in the conflict.

He was accused of being insensitive to Jews and Holocaust survivors, in a week when many will celebrate the festival of Passover.

"I mistakenly used an inappropriate and insensitive reference to the Holocaust, to which frankly there is no comparison," Spicer said at a media event in Washington.

"For that I apologise, it was a mistake to do that… I'm not in any way standing by them, I was trying to draw a comparison to which there shouldn't have been.”

"I mistakenly used an inappropriate and insensitive reference to the Holocaust, to which frankly there is no comparison," Sean Spicer

Spicer raised eyebrows in the White House press room when he made the statement that the infamous German dictator had not used chemical weapons during the Holocaust.

"We didn’t use chemical weapons in world war two. You had someone as despicable as Hitler who didn’t even sink to using chemical weapons," he said earlier in the week.

Democratic leader Nancy Pelosi released a statement in which she criticised Spicer's comments, and called on President Trump to fire his press secretary.

"Sean Spicer must be fired, and the President must immediately disavow his spokesman’s statements," Pelosi said. "Either he is speaking for the President, or the President should have known better than to hire him."