Rabbis chanted mournful prayers for the dead that reverberated over the crematoria, barracks and watchtowers of Auschwitz-Birkenau on Thursday, the 66th anniversary of the death camp's liberation.

As darkness fell, names of Hitler's victims were read out over loudspeakers in a recitation that seemed long but ultimately included but a fraction of the 1.1 million Jews, Gypsies and others murdered at Nazi Germany's most notorious death camp.

Christian clerics also prayed at a gathering that included the Polish and German presidents, diplomats and Holocaust survivors. Former camp inmates, many moving tentatively with canes, wore blue-and-white striped scarves that evoked the look of the prisoner garb they once wore.

Earlier, Germany's President Christian Wulff stood in silence before a gray concrete wall where Nazis executed Polish resistance members at Auschwitz, one gesture among many Thursday symbolizing his nation's remorse for the suffering inflicted during World War II.

Wulff and Polish President Bronislaw Komorowski laid wreaths at the wall and walked with former camp inmates beneath the entrance gate bearing the inscription "Arbeit Macht Frei" — or "Work Sets You Free" — a notorious slogan used by the Nazis in camps where they subjected their victims to slave labor, torture and murder.

The two leaders then traveled the short distance to Birkenau, the vast camp where people were brought by train from all across Europe to be killed with factory-like efficiency in gas chambers.

"The name Auschwitz stands unlike anything else for the crimes perpetuated by Germans against millions of human beings," Wulff said in a speech. "They fill us Germans with disgust and shame. They lay upon us a historical responsibility that is independent of individual guilt. We must never again allow such crimes. And we must keep the memories alive."

The ceremony at Auschwitz is one of several being held across the world on International Holocaust Remembrance Day, the global day of commemoration established by the United Nations in 2005. The date was picked to coincide with the anniversary of Auschwitz's liberation by Soviet troops on Jan. 27, 1945.

U.N. Secretary-General Ban Ki-moon said the world body was paying special tribute this year to the women who suffered in the Holocaust.

"They joined the resistance, rescued those in peril, smuggled food into ghettos and made wrenching sacrifices to keep their children alive," he said. "Their courage continues to inspire."

In Berlin, the German parliament convened Thursday for a special session commemorating the victims of the Holocaust.

Parliament speaker Norbert Lammert told lawmakers it is the duty of later generations to keep alive the memory of those murdered by German Nazis.

For the first time, a survivor representing Gypsies addressed the body. Zoni Weisz reminded lawmakers of what he called the "forgotten Holocaust" against 500,000 of his people.

Romani Rose, chairman of the Central Council of German Sinti and Roma, also recalled the suffering of his people during the events at Auschwitz, noting that "practically every family from our minority has been affected by the Holocaust."

He also warned that right-wing hatred is again killing Roma, today Europe's largest ethnic minority, noting that 11 Hungarian Roma have been killed since 2008 by neo-Nazis in "a new dimension of violence against our minority."

Political prisoners, Poles, gays and lesbians, Jehovah's Witnesses and Soviet prisoners of war were also killed en masse by the Nazis, along with nearly 6 million Jews.

"To label people as unworthy and order their destruction and, finally, to systematically murder millions in an industrialized fashion — that is unique in human history," Lammert said. "The memory of those events and aberrations obliges us to respect all people equally ... and to confront violations of human rights in Germany and everywhere else in the world."

Separate ceremonies were held elsewhere in Germany, including at the Buchenwald concentration camp, where elderly survivors gathered, and at a new memorial in the former factory of the company that made the crematoria ovens for Auschwitz-Birkenau.

Also Thursday, Turkey was holding its first official commemorations on international Holocaust remembrance day. Istanbul's governor and other officials were to join members of Turkey's Jewish community to remember the victims of Nazi death camps.

In a message ahead of the ceremony, Turkey said it would continue to remember the Holocaust and draw lessons to combat "racism, xenophobia and anti-Semitism." The ceremony comes amid a serious rift between Turkey and Israel over the Jewish state's treatment of Palestinians.

Nazi Germany opened Auschwitz as a concentration camp in the summer of 1940 after it invaded and occupied Poland, and its first prisoners were Poles. Because of its location in the heart of Europe, Germany soon turned it into a center for implementing the "Final Solution," the plan to kill Europe's Jews.

By the time of its liberation, at least 1.1 million people had died in the gas chambers at Auschwitz-Birkenau or from starvation, disease and forced labor.