MSNBC host Rachel Maddow's show account on Twitter was forced to delete a segment of a guest comparing Russian President Vladimir Putin to Adolf Hitler after it was fact-checked by the Auschwitz Memorial.

Appearing on "The Rachel Maddow Show" last week, former U.S. Ambassador to Russia and Stanford University Professor Michael McFaul provided a more favorable view of the Nazi dictator, echoing a Ukrainian reporter who claimed that Putin was showing increased aggression compared to Hitler because the Russian dictator is killing his own people.

Michael McFaul, U.S. Ambassador to the Russian Federation, looks on during his speech at the New Economic School in Moscow June 7, 2012.

Michael McFaul, U.S. Ambassador to the Russian Federation, looks on during his speech at the New Economic School in Moscow June 7, 2012.

"One of the Russian journalists said, 'You know, there's one difference between Hitler when he was coming in and Putin. Hitler didn't kill ethnic Germans. He didn't kill German-speaking people," McFaul said to guest host Ali Velshi on Friday. 

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"I think people need to remember that we're talking about cities like Kharkiv and Mariupol and Kyiv. There are large populations there, you know, up to a third and sometimes as much to a half that are Russian speakers and are ethnic Russians. And yet Putin doesn't seem to care about that. He slaughters the very people he said he has come to liberate," McFaul said. 

The segment was later shared by the Maddow Blog on Twitter, with the caption, "One difference between Putin and Hitler is that Hitler didn't kill ethnic Germans, German-speaking people. Putin slaughters the very people he said he has come to liberate."

The remarks prompted immediate backlash on social media, eventually catching the attention of The Auschwitz Memorial.

"On a factual note: Hitler did kill ethnic Germans & German-speaking people: those who opposed the Nazi regime, those who resisted, those who did not fit into the ‘Weltanschauung,'" the Auschwitz Memorial account replied to the show's tweet after the interview.

By late Saturday, the show had taken down the post, and issued a correction emphasizing that contrary to what McFaul asserted, Hitler did indeed kill "millions of Germans."

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"The historical record is clear," the show tweeted. "Hitler killed millions of Germans. We tweeted out part of an inaccurate statement made last night by former Ambassador Michael McFaul without attribution, and we regret doing so. We have since removed the tweet."

 McFaul also walked back his comments on Saturday, telling viewers that he "slipped late last night and violated an unwritten taboo-- never compare Hitler with anyone. I agree. He was incomparably evil. I won't do it again."

Former U.S. Ambassdaor to Russian Michael McFaul listens to a question while testifying before a House Intelligence Committee hearing titled "Putin's Playbook." REUTERS/Brendan McDermid

Former U.S. Ambassdaor to Russian Michael McFaul listens to a question while testifying before a House Intelligence Committee hearing titled "Putin's Playbook." REUTERS/Brendan McDermid

He did however go on to defend himself in combative exchanges with other Twitter users, telling one, "Of course, I know about the millions of German-speakers and people with German nationality that Hitler killed. I genuinely want to learn more about the ethnic German civilians living outside of Germany that Hitler consciously slaughtered. I don't know that history," also writing, "Yes, I know the difference between ethnic identities and state nationalities. But thanks all for the reminders."

Fox News' Joseph A. Wulfsohn contributed to this report.