Jewish human rights group The Simon Wiesenthal Center on Friday called on Dutch Prime Minister Mark Rutte to rescind approval for a rally in support of ISIS in the Hague, after protesters, yelling in Arabic and Dutch, proclaimed that “dirty Jews from the sewers” should be killed.

In a fiery letter to Rutte, Dr. Shimon Samuels, SWC Director for International Relations, said similar calls of violence were reported at a rally on July 4, and show that rather than even expressing support for Hamas militants in Gaza, the true intention of the rallies have been to call for the death of Jews.

“Yesterday, the call in Arabic and Dutch was for ‘dirty Jews from the sewers to be killed,'” Samuels said. “This rally had little to do with Gaza solidarity. It was unambiguously targeted against Jews, but also according to the Dutch press sought to lynch journalists, who were pulled to safety by the police, otherwise serving as silent spectators.”

He said that what was “most disturbing” was that, while press reports and photos from the rally show the mass of masked demonstrators calling for violence, the official Public Prosecutor’s press release stated “there were only 40 to 50 people present,” that “the police were present with an Arabic speaking police officer” and “the slogans overheard by this officer were not considered as crossing boundaries. Hence no arrest was made.”

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Samuels told the Dutch prime minister, “The YouTube clip clearly shows many more than 50 participants and the slogans at the end of the clip were repeated and quite evident, ‘Maut al-Yahud’ (Death to the Jews), ‘Khaybar, Khaybar’ (The genocide of the Jews of Khaybar) and ‘Those who do not jump are Jews’ (All the Muslims present jumped).”

“Our Center expects you to launch an immediate inquiry into the cover-up by this police officer who betrayed his duty to faithfully translate all slogans – most of which were menacing Jews,” Samuels said, urging the Netherlands “to follow the example of the United Kingdom in banning ISIS and to forbid any further demonstrations in Holland that call for the murder of Jews or any other ‘riff-raff’.”

Samuels’s letter noted that Adberazak Khoulani, Islamic Dutch Unity Party leader, is publicly endorsing ISIS in Iraq, proclaiming ‘Long live ISIS… and Insha’Allah on to Baghdad to fight the riff-raff there… sometimes violence is necessary?'”

Samuels said Khoulani’s “language, in fact by implication, applauds ISIS destruction of the ancient Christian communities in Iraq and Syria, mass-murdered together with thousands of Shi’a Muslims in the territory over-run by ISIS, which they claim as their new Caliphate.”

He said that if Khoulani and his Dutch supporters of Jihadism have there way, “Baghdad will have come to the Hague.”

Samuels said that when the Christen Unite Group also called to ban ISIS demonstrations, Dutch Foreign Minister Frans Timmermans argued for the “Dutch right to demonstrate,” rejecting exceptions when public order is endangered, while Justice Minister Ivo Opstelten “has amazingly sent a letter to Parliament claiming that ‘openly sympathizing with terrorist groups is not punishable by law.'”

Samuels said, “ISIS is a terrorist organisation that split from Al-Qaeda, which it considered too moderate, yet Hague Mayor Jozias Van Aartsen – who is also in charge of the city’s police – for the second time authorized the rally, reportedly stating, ‘no boundaries have been crossed during the demonstration.'”

Samuels said the government’s policy is “suicidal” and “could perhaps be best understood in the context of Van Aartsen’s political preferences, as seen in his past ties with such figures as [dead PLO leader Yasir] Arafat and [condemned Yugoslavian leader Slobodan] MiloÅ¡eviÄ‡.”

“At least in World War II, the Netherlands put up a fight against the Nazis,” Samuels said, concluding his letter to the Dutch prime minister.

Watch the hate-fill rally in the Hague: