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WARSAW, Poland — The world marked International Holocaust Remembrance Day on Sunday amid a revival of hate-inspired violence and signs that younger generations know less and less about the genocide of Jews, Roma and others during World War II.

In Poland, which was under Nazi German occupation during the war, a far-right activist who has been imprisoned for burning the effigy of a Jew gathered with other nationalists Sunday outside the former death camp of Auschwitz ahead of official ceremonies remembering the 1.1 million people murdered there.

Since last year's observances, an 85-year-old French Holocaust survivor, Mireille Knoll, was fatally stabbed in Paris and 11 Jews were gunned down in a Pittsburgh synagogue during Shabbat services, the deadliest attack on Jews in U.S. history.

People walk through the main gate of the German Nazi death camp Auschwitz-Birkenau in Poland on Jan. 27, 2019. Ceremonies marked the camp's liberation from the Nazi's 74 years ago. Janek Skarzynski / AFP - Getty Images

Human Rights First, a U.S. organization, recalled those killings and warned that "today's threats do not come solely from the fringe."

"In places such as Hungary and Poland, once proudly democratic nations, government leaders are traveling the road to authoritarianism," said Ira Forman, the group's senior adviser for combating anti-Semitism. "As they do so, they are distorting history to spin a fable about their nations and the Holocaust."

The Polish nationalist, Piotr Rybak, said his group was protesting the official observances at Auschwitz, claiming they remember only murdered Jews and not murdered Poles.

That accusation is incorrect. The observances at the state-run memorial site pay homage each Jan. 27 to all of the camp's victims, both Jews and gentiles.

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Counter-protesters at Auschwitz on Sunday held up a "Fascism Stop" sign and an Israeli flag, while police kept the two groups apart.

Former Auschwitz prisoners placed flowers Sunday at an execution wall at Auschwitz. They wore striped scarves that recalled their uniforms, some with the red letter "P," the symbol the Germans used to mark them as Poles.

Early in World War II, most prisoners were Poles, rounded up by the occupying German forces. Later, Auschwitz was transformed into a mass killing site for Jews, Roma and others, operating until the liberation by Soviet forces on Jan. 27, 1945.

In Germany, Foreign Minister Heiko Maas warned in an op-ed in the weekly Welt am Sonntag that across Europe populists are propagating nationalism and "far-right provocateurs are trying to downplay the Holocaust."

"We shall never forget. We shall never be indifferent. We must stand up for our liberal democracy," Maas wrote.

The Holocaust Memorial in Berlin on Jan. 27, 2019. Markus Schreiber / AP

Over the past year, Germany has seen a rising number of often violent attacks against Jews carried out by neo-Nazis and Muslims, prompting the government to appoint a commissioner against anti-Semitism and to start funding a national registration office for anti-Semitic hate crimes.

The clashes of views at Auschwitz come amid a surge of right-wing extremism in Poland and elsewhere in the West. It is fed by a broader grievance many Poles have that their suffering during the war at German hands is little known abroad while there is greater knowledge of the Jewish tragedy.

However recent surveys show that knowledge of the atrocities during World War II is declining generally.

A new study released in recent days by the Conference on Jewish Material Claims Against Germany and the Azrieli Foundation found that 52 percent of millennials in Canada cannot name even one concentration camp or ghetto and 62 percent of millennials did not know that 6 million Jews were killed in the Holocaust.

Its findings were similar to a similar study carried out a year before in the United States.

In Britain, a new poll by the Holocaust Memorial Day Trust found that one in 20 adults in Britain do not believe the Holocaust took place.

The poll of more than 2,000 people released Sunday also found that nearly two-thirds of those polled either did not know how many Jews had been murdered or greatly underestimated the number killed during the Holocaust.

"Such widespread ignorance and even denial is shocking," chief executive Olivia Marks-Woldman said.

Israel's Ministry of Diaspora Affairs said in its Global Antisemitism Report released Sunday that 13 Jews were murdered in fatal attacks in 2018, marking the highest number of Jews murdered since a wave of attacks on Argentinian Jews in the 1990s.

The report found that around 70 percent of anti-Jewish attacks were anti-Israel in nature and that most of the attacks were led by neo-Nazis and white supremacists.

The United Nations recognized Jan. 27 as International Holocaust Remembrance Day in 2005.