Israel has reacted with fury after Russia's foreign minister claimed that Nazi leader Adolf Hitler "had Jewish blood".
Sergei Lavrov made the comments to try to justify Russia's portrayal of Ukraine as "Nazi" despite the fact that its president is Jewish.
Israel's foreign ministry summoned Russia's ambassador for "clarification" and demanded an apology.
Nazi Germany murdered six million Jews in the Holocaust in World War Two.
Mr Lavrov made the remarks in an interview on Italian TV programme Zona Bianca on Sunday, days after Israel marked Holocaust Remembrance Day, one of the most solemn occasions in the Israeli calendar.
When asked how Russia can claim that it is fighting to "de-Nazify" Ukraine when President Volodymyr Zelensky is himself Jewish, Mr Lavrov said: "I could be wrong, but Hitler also had Jewish blood. [That Zelensky is Jewish] means absolutely nothing. Wise Jewish people say that the most ardent anti-Semites are usually Jews."
The minister's statement was met with outrage across Israel's political spectrum.
Israeli Prime Minister Naftali Bennett said: "Such lies are meant to blame the Jews themselves for the most terrible crimes in history and thus free the oppressors of the Jews from their responsibility.
"No war today is the Holocaust or is like the Holocaust."
Israeli foreign minister Yair Lapid reacted angrily, calling Mr Lavrov's words "unforgivable".
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Mr Lavrov was also condemned by the head of Israel's Yad Vashem Holocaust memorial, Dani Dayan.
"Most of his remarks are absurd, delusional, dangerous and deserving of any condemnation," he tweeted. "Lavrov deals with the reversal of the Holocaust: turning the victims into criminals, based on the promotion of a completely unfounded claim that Hitler was of Jewish descent."
In a video address, President Zelensky said: "I have no words... No one has heard any denial or any justification from Moscow. All we have from there is silence".
The Ukrainian president added that the silence indicates the Russian leadership had either forgotten "all the lessons of World War Two" or "perhaps they have never learned those lessons".
US State Department spokesman Ned Price said Mr Lavrov's comments showed "the lowest form of racism" and "insidious lies".
He added that "the Kremlin is consistently proving that there is no floor when it comes to just how low they can stoop", and Mr Lavrov's claims are "the latest example of that".
The BBC's Jon Donnison in Jerusalem says the strength of the reaction reflects just how deeply offensive and unconscionable Mr Lavrov's comments will be to Jews, both in Israel and around the world. Over recent months, Israel, which has a large Russian population, has tried at times to act as a mediator between Russia and Ukraine.
But, he says, the Israeli government has faced some criticism for not taking a tough enough line with President Vladimir Putin. Mr Lavrov's comments will test Israel's relations with Russia and while offensive to many, they reflect a common narrative amongst the Kremlin's supporters, our correspondent adds.
Ukraine's foreign minister rebuked Mr Lavrov, saying his remarks were evidence of Russia's own "deep-rooted anti-Semitism".
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There have for decades been unproven claims that Hitler's unidentified paternal grandfather was Jewish, fuelled by an assertion by Hitler's lawyer Hans Frank.
In his memoir, published in 1953, Frank said he had been instructed by Hitler to investigate rumours that he had Jewish ancestry. Frank said he uncovered evidence that Hitler's grandfather was indeed Jewish - though the claim, which has gained ground among conspiracy theorists, has been treated with scepticism by mainstream historians.