By Barbara Erling and Kuba Stezycki OSWIECIM, Poland (Reuters) -Auschwitz survivors were being joined by world leaders on Monday to mark the 80th anniversary of the liberation of the Nazi German death camp by Soviet troops,

Survivors of the Nazi's notorious Auschwitz death camp are taking center stage at the memorial service to mark 80 years since its liberation by Soviet troops.

Silence pervades the site of Auschwitz-Birkenau today. Sometimes the only sounds are the soft footsteps of visitors, people who come from all over the world to mourn and to learn, and the voices of their guides speaking in hushed tones into microphones trying to explain the ungraspable.

It doesn’t do any good for your heart, for your mind, for anything,” said Holocaust survivor Jona Laks, 94, about her return to Nazi Germany’s Auschwitz-Birkenau concentration camp.

In just over four-and-a-half years, Nazi Germany systematically murdered at least 1.1 million people at Auschwitz, built in the south of occupied Poland near the town of Oswiecim. Auschwitz was at the centre of the Nazi campaign to eradicate Europe's Jewish population, and almost one million of those who died there were Jews.

Auschwitz survivors have warned of the rising antisemitism and hatred in the modern world as they gathered with world leaders and European royalty on the 80th anniversary of the death camp’s liberation.

The 80th anniversary of the liberation of Auschwitz by Soviet troops was observed at the site of the former Nazi death camp.

The ceremony is widely regarded as the last major observance likely to see a significant number of survivors in attendance.

In all, the Nazi regime murdered 6 million Jews from all over Europe, annihilating two-thirds of Europe's Jews and one-third of all Jews worldwide. In 2005, the United Nations designated Jan. 27 as International Holocaust Remembrance Day.

Jan. 27, marks International Holocaust Day. NBC News' Jay Gray reports from Auschwitz, where the 80th anniversary of its liberation will bring forth memories and messages that resonate today.

Watch as Holocaust survivors returned to Auschwitz in Poland on Monday, 27 January, marking 80 years since the concentration camp was liberated. Holocaust Memorial Day is held yearly on 27 January to commemorate the memory of the six million Jews and other groups who the Nazis murdered in the Holocaust.