Israeli has condemned the spraying of anti-Zionist graffiti at the Yad Vashem Holocaust Museum in Jerusalem.
Suspicion has fallen on ultra-Orthodox opponents of the state of Israel.
Among the slogans reportedly spray-painted in Hebrew at 10 spots across the memorial compound Sunday were: "If Hitler had not existed, the Zionists would have invented him"; "Hitler, thanks for the Holocaust"; "Israel is the secular Auschwitz of the Sephardic Jewry"; and "Jews wake up — the Zionist regime is dangerous."
Yad Vashem commemorates the six million Jews killed by the Nazi regime during World War II.
Areas of the museum attacked included the red-brick Wall of Remembrance in Warsaw Ghetto Square and the cattle car memorial, which represents how millions of Jews were transported to the Nazi death camps from all parts if Europe, Agence France-Presse reported.
"This unprecedented act crosses a red line," Yad Vashem chairman Avner Shalev said in a statement posted on the Yad Vashem website.
"I am shocked and stunned by this callous expression of burning hatred against Zionists and Zionism."
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According to the Associated Press, Shalev said the slogans were written in excellent Hebrew handwriting and one was signed "world ultra-Orthodox Jewry."
Many Ultra-Orthodox Jews are anti-Zionist, maintaining that a Jewish state should not have been established before the coming of the Messiah. One conspiracy theory holds that Israel's founders colluded with Hitler.
AFP cited police spokesman Micky Rosenfeld as saying an investigation had been opened.