Hebrew black graffiti thanking the Nazi leader Adolf Hitler for the Holocaust and denouncing Zionism were sprayed inside the Yad Vashem Holocaust museum in Jerusalem.
Seven giant slogans, including one which read: "Thank you Hitler for your wonderful Holocaust that you arranged for us, it's only because of you that we got a state at the UN" were sprayed in Warsaw Ghetto Square near the sculpture depicting the Warsaw Ghetto uprising.
Another reads: "Jews, wake up, the evil regime does not protect us, it only endangers us.”
More graffiti was sprayed next to the cattle car memorial, which remembers how millions of Jews were transported from all over Europe to the Nazi death camps.
Other slogans read: "The Zionist leadership wanted the Holocaust" and "If Hitler hadn't existed, the Zionists would have invented him."
Another said: "The war of the Zionist regime is not the war of the Jewish people," fuelling suspicion that a small fringe of ultra-Orthodox Jews, who are virulently opposed to the state of Israel, were to blame.
The red, white and black graffiti was written in both formal Hebrew characters as well as in hand-written script and signed "The global cynical mafia."
Police spokesman Micky Rosenfeld confirmed basic details of the incident, and said an investigation had been opened.
He said it was not clear who was responsible, whether it was "youngsters, vandals or people acting from other motives."
"We must investigate and deal quickly with these despicable acts," Jerusalem Police Chief Nisso Shaham said, calling the incident "a shocking event" in which one of Israel's important symbols was attacked.
Yad Vashem is the main memorial and museum in Israel commemorating the six million Jews who were killed by the Nazi regime during World War II.
“We know that the Yad Vashem Memorial is a link between Israeli society and Judaism," the museum's chairman Avner Shalev said Monday.
"All of the messages written here are aimed at disrupting this connection,” he added.
"This unprecedented act crosses a red line," he said in a statement issued by Yad Vashem, which said 10 pieces of "scathing graffiti" had been found at the site.
"The particularly disturbing slurs included poisonous attacks on Zionism. The main motif was that Zionism caused the Holocaust," the statement said.
"We are shocked and dazed by this callous expression of burning hatred against the Zionists and Zionism," Shalev added.
Speaking to Israel's army radio, Shalev said the text pointed to the involvement of ultra-Orthodox extremists.
"One of the slogans was signed with the words 'World Haredi Jewry,'" he said, using the Hebrew word for ultra-Orthodox Jews, indicating that police were checking CCTV footage from cameras positioned around the site.
Fuelling suspicion of ultra-Orthodox involvement, another slogan read: "The war of the Zionist regime is not the war of the Jewish people."
The red, white and black graffiti was written both in formal Hebrew characters and in handwriting, and signed "The global cynical mafia."
Israel’s Education Minister Gideon Sa'ar said he was shocked that the vandals desecrated the museum with the intention of offending public sensibilities.
He said he trusted that the Israel Police would know how to track down the criminals and bring them to justice.