Survivors of the Nazis' Sachsenhausen concentration camp, situated near Berlin, have gathered for the burial of recently discovered ashes of tens of thousands of inmates who perished there. 150 urns, each holding 30 kilograms of ashes, were buried near the camp's former crematorium in a joint Christian and Jewish ceremony. The names of some victims were read aloud in symbolic tribute to all of those who died. A layer of ashes up to one and a half meters thick was unearthed last year as archaeologists worked on a concrete building constructed near the camp's former crematorium by East Germany's communist authorities as a memorial. Though impossible to establish the number or identity of the victims whose cremated remains were found, memorial director Günter Morsch estimated that there were tens of thousands. Overall, some 200,000 people were interned between 1936 and 1945 at Sachsenhausen, one of the first concentration camps of Nazi Germany. The burial comes ahead of commemorations next month marking the camp's liberation in April 1945, which some 500 survivors are expected.