BABI YAR, Ukraine – No Ukrainian has the right to forget the Babi Yar massacre, Ukrainian President Petro Poroshenko said Thursday night at the state ceremony to mark 75 years since the Babi Yar slaughter.“There have been those for which one felt shame. And this, too, cannot be erased from our collective memory,” Poroshenko said, talking to a large audience at the site of the mass killings by Germans and their accomplices exactly 75 years ago. “Collaborators have left their mark in almost all Nazi-occupied European countries, but they do not represent their people.”The event, attended by world leaders and dignitaries, was the climax of a week full of dozens of events of various formats to commemorate the massacre.This was by far the largest commemoration of Babi Yar in the country, and stood in sharp contrast with its years under Soviet rule, in which the crimes against Jews on Ukrainian soil were deliberately covered up.Among the 150,000 victims thought to be buried at the Babi Yar ravine, there are 33,771 Jews who were killed in just two days, September 29 and 30, 1941.President Reuven Rivlin had been due to speak at the ceremony, but rushed home to Israel upon receiving news of the death of his predecessor, Shimon Peres. During the short time that he was in Kiev, however, Rivlin made waves with a speech he delivered to parliament on Tuesday. In that speech, he told Ukrainian lawmakers that many of the crimes committed against Jews were perpetrated by Ukrainians, particularly members of the nationalist Ukrainian Insurgent Army. This drew the ire of nationalist politicians and other key figures in Ukraine.“What Rivlin did can unambiguously be interpreted as spitting in the face of Ukrainians,” especially at a time when the people he accused of perpetrating crimes are no longer alive to defend themselves, said Bogdan Chervak, the first deputy chairman on the State Committee for Television and Radio of Ukraine. Volodymyr Vyatorovych, director of the Ukrainian Institute of National Remembrance of Ukraine, accused Israel’s president of repeating a Soviet “myth” about Ukrainians’ complicity in the Holocaust.But Poroshenko’s remarks Thursday appeared to acknowledge that Ukrainians played a role in the tragedy.“We have a moral obligation to remember all the victims of the Nazis,” he said at a reception, several hours before the state ceremony. “We shouldn’t forget even a single human life. Every single name should be remembered. We have to remember the lessons and price of inaction, and remember the outcome of the policy of appeasement.“Today we are paying tribute to thousands of innocent people who were killed in Babi Yar, and we are asking how to prevent this kind of crime in the future,” he continued.Earlier that day, Proshenko announced that a Holocaust memorial center would be established at Babi Yar.Among those present at the state ceremony were Deputy Knesset Speaker Tali Ploskov, Chief Rabbi of Ukraine Yaakov Dov Bleich, President of Hungary János Áder, President of the European Council Donald Tusk, President of Germany Joachim Gauck and US Secretary of Commerce Penny Pritzker.Addressing the audience, Gauck said that Germans must “approach Babi Yar with unspeakable guilt... Here the goal of the Nazis was not conquest, but the destruction of an entire people,” he said, adding that Babi Yar symbolizes the “industrial killing of people.”The ceremony was organized in collaboration with the Ukrainian Jewish Encounter initiative and the World Jewish Congress, whose CEO and Executive Vice President Robert Singer described the massacre as an event which remains incomprehensible. “It is not easy for us to be here today. It is not easy for Jews, for Ukrainians, for Germans, for anyone,” he said.“Babi Yar was not just a German crime,” he said pointedly.“No more than the Holocaust was perpetrated by the Third Reich alone. Practically every occupied country in Europe helped the Germans round up their Jews, and Ukrainians were no exception. Too many of those who did not help the Nazis, conveniently looked the other way. Too many ordinary people watched as their Jewish neighbors were taken away, and pretended that they didn’t see.”But Singer expressed gratitude to the Ukrainian government and Poroshenko for turning that around. “It is an important step in the right direction,” he asserted. “The world can finally acknowledge who these people were, and why they died.”Singer also paid tribute to those Ukrainians who joined the Red Army in fighting the Nazis, and those who saved their Jewish neighbors from certain death.At a dinner hosted Wednesday evening by the World Jewish Congress, the Ukrainian Confederation of Jews and Ukrainian Jewish Encounter, Ukrainian writer and Soviet dissident Ivan Dziuba was awarded the Sheptytsky Award. Dziuba was vocal about the Jewish victims of Babi Yar as early as the 1960s. He wrote Internationalism or Russification? a widely translated critique of Soviet policies published in the West in 1968 that led to his arrest and enforced professional isolation.World Jewish Congress President Ronald Lauder praised Dziuba for his “great moral courage.” Lauder, who had planned on speaking at the state ceremony but flew back to Israel for Peres’s funeral, addressed the subject of the Babi Yar commemoration in a speech Wednesday night.After talking about the tragedy of the massacre, and praising those Ukrainians who resisted the Nazi regime and sheltered Jews, Lauder ended on a positive note, alluding to a “rebirth of a strong Jewish community” in Ukraine. “This rebirth is nothing short of a miracle,” he said. “Just 25 years ago, during the Soviet era, Jews here in Kiev were not allowed to practice their faith, and they were singled out by the Soviet government because they were Jewish. So tonight we mark this tremendous change.”JTA contributed to this report.