Archaeologists in Berlin have unearthed a large number of human bones from a site close to where Nazi scientists carried out research on body parts of death camp victims sent to them by sadistic SS doctor Josef Mengele, officials said Thursday.

In his first visit to Auschwitz in his capacity as leader of the Catholic Church, Pope Francis prayed and met with survivors during a five-day trip to Poland that included meetings with young Catholic pilgrims gathering in Krakow for World Youth Day, a global celebration of faith.

Israel marked Yom Hashoah, its annual Holocaust Remembrance Day, on Thursday in memory of the six million Jews murdered by Nazi Germany and its collaborators during World War II.

Princeton professor Jan Tomasz Gross said Poland's new stance on dissociating itself from the Holocaust is "a step back to the dark ages of anti-Semitism," while he decried other anti-democratic policies adopted by the new Polish government.

Treblinka holds a notorious place in history as nearly all Jews brought there were immediately killed. After a prisoner revolt in the camp, Samuel Willenberg managed to escape and lived to tell the truth about the Nazi attempt to exterminate the Jews as well as Polish complicity in the Holocaust.