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Russia has doubled down on claims that Adolf Hitler may have had "Jewish blood", accused Israel of backing Neo-Nazis and said its foreign minister was "anti-historical" in his condemnation of Moscow's comments.
The comments sparked outrage around the world, especially in Israel.
Israeli Foreign Minister Yair Lapid on Monday condemned his Russian counterpart Sergey Lavrov for making an "unforgivable and outrageous statement as well as a terrible historical error" and summoned Moscow's ambassador for "clarifications".
"Jews did not murder themselves in the Holocaust," he said. "The lowest level of racism against Jews is to accuse Jews themselves of anti-Semitism.
"The Ukrainians aren't Nazis. Only the Nazis were Nazis and only they dealt with the systematic destruction of the Jewish people," Mr Lapid told the YNet news website.
Israeli Prime Minister Naftali Bennett also denounced Mr Lavrov's "lies" that he said effectively "accuse the Jews themselves of the most awful crimes in history", perpetrated against themselves.
Russia hit back on Tuesday.
"We have paid attention to Foreign Minister Yair Lapid's anti-historical remarks, which largely explain the current government's decision to support the neo-Nazi regime in Kyiv," the Russian Foreign Ministry said in a statement.
Mr Lavrov, speaking to Italian outlet Mediaset's Rete 4 channel, had claimed that Ukrainian President Volodymyr Zelenskyy "puts forward an argument of what kind of Nazism can they have if he himself is Jewish".
"The Jewish origins of the president [Zelenskyy] is not a guarantee of protection against rampant neo-Nazism in the country.
"History, unfortunately, knows tragic examples of co-operation between Jews and Nazis."
Mr Lavrov, according to a transcript posted on the Russian Foreign Ministry website, then added: "I could be wrong, but Hitler also had Jewish blood."
One of the justifications offered by Moscow for its February "special military operation" was to "de-Nazify Ukraine".
Mr Zelenskyy used his nightly address on Monday to condemn Mr Lavrov's comments.
“Such an anti-Semitic attack by their minister means that Russian authorities have forgotten all the lessons of the Second World War, or maybe they never learnt those lessons.”
He accused the Russian minister of deliberately trying to tie Ukraine’s Jews, such as himself, with Nazism.
“All of this is not accidental. The words of the Russian foreign minister, a ‘great connoisseur of Hitlerism’, are not random,” he said.
He asked if Israel would keep its ambassador in Moscow given the clear position it was taking.
Israel has expressed support for Ukraine since the invasion in February. However, Israel initially avoided direct criticism of Moscow and has not enforced formal sanctions on Russian oligarchs.
However, ties have grown more strained, with Mr Lapid last month accusing Russia of committing war crimes in Ukraine.
Several Western officials have also denounced Mr Lavrov's comments.
Italian Prime Minister Mario Draghi called the his comments obscene, while Canada's Justin Trudeau voiced his disbelief.
US State Department spokesman Ned Price said Mr Lavrov’s comments were “the lowest form of racism ... the lowest form of propaganda”.
Dani Dayan, chairman of Yad Vashem, Israel's memorial to the 6 million Jews killed in the Holocaust, said the Russian minister was spreading "an anti-Semitic conspiracy theory with no basis in fact".
Hitler's 'Jewish' blood: an old conspiracy theory
The identity of one of Hitler's grandfathers is not known but there has been some speculation, never backed up by any evidence, that he might have been a Jew.
Austrian historian Roman Sandgruber told AFP that the rumour of Hitler’s Jewish ancestry began circulating in the 1920s and was encouraged by his political rivals as he started rising to power.
Then after the Second World War, the memoirs of Nazi war criminal Hans Frank, who governed occupied Poland during the war, revived the story.
He claimed that Hitler had asked him to investigate the identity of his unknown paternal grandfather.
While Frank claimed Hitler’s grandmother had worked as a cook for a Jewish family in the Austrian city of Graz, where she was then paid maintenance until Hitler’s father was 14, Mr Sandgruber says there is no solid evidence to the story.
For example, he points out that Jews were not allowed to live in Graz at the time.
“So, who was Hitler's grandfather? "This is a question without an answer," historian Ofer Aderet wrote in Israel's Haaretz newspaper on Monday.
"Other reports claimed that Hitler's persecution of the Jews resulted from feelings of shame about his partial Jewish ancestry.
"The bottom line, though, is that there is no historical proof for any of this."