Flowers in front of a memorial stone near the gas chamber of the former Nazi concentration camp in Natzwiller-Struthof, eastern France, on April 26, 2015
Natzwiller (France) (AFP) - European leaders on Sunday remembered the atrocities of concentration camps run by the Nazis and their allies during the Second World War with ceremonies in Germany, Croatia and France.
At the site of the Bergen-Belsen concentration camp in Germany the president of the World Jewish Congress, Ronald Lauder, recalled the shock of the first images to emerge from the camp when it was liberated 70 years ago.
"We saw the bulldozers pushing naked bodies into open pits. The walking skeletons. The unbelievable sadness and loss," he said at a ceremony attended by around 70 survivors.
The sombre and emotional scenes were mirrored at Jasenovac in Croatia, where families, officials and diplomats gathered to remember the tens of thousands of victims, mostly Serbs and Jews, who were killed in one of the war's most brutal concentration camps.
In France, President Francois Hollande warned that the continued existence of racism and anti-Semitism meant "the worst could yet return", as he led commemorations at Struthof in the Alsace region, site of the only Nazi camp on French soil.
More than 50,000 deportees from across Europe lost their lives at the Bergen-Belsen camp in western Germany between 1941 and 1945, including the young Jewish diarist Anne Frank, in addition to 20,000 prisoners of war.
German President Joachim Gauck paid tribute to the British soldiers who freed the camp and restored "humanity" to the country.
"With their actions and their approach, driven by humanity, a new epoch began. People, the former 'master race', would see that human sympathy can indeed be learned," said Gauck.
"As such, they were the shining counter-example to the advancing Germans who in the years before conquered, subjugated, enslaved and plundered Europe."
- The horrors of Jasenovac -
In Croatia, the commemorations marked the 70th anniversary of an attempted escape by around 600 inmates from the Jasenovac death camp, known as "Croatia's Auschwitz".
The United States Holocaust Memorial Museum estimates that 100,000 people -- mainly Serbs, Jews, Roma and anti-fascist Croatians -- were killed there. Serbia claims the figure could be as high as 700,000.
Many had their throats cut with specially designed knives. Others were burned alive in furnaces.
As anti-Nazi partisans approached shortly after the escape attempt, the prison guards abandoned the camp, killing remaining inmates and burning down the buildings and torture chambers as they left.
"The horrors of Jasenovac warn us... not to allow discrimination and persecution based on national, religious, ideological or gender differences ever again," parliamentary speaker Josip Leko said.
Croatia has sought to distance itself from the pro-Nazi Ustasha regime which set up the camp in 1941 and focus on the country's anti-Nazi partisans.
"There was only one Croatian army during World War II and these were Croatian partisans," said Prime Minister Zoran Milanovic.
- 'Fight has not ended' -
France marked the National Day of Deportation on Sunday, recalling the role the collaborationist French regime played in assisting the Nazi genocide.
Its leaders drew comparisons with current affairs, as concern over anti-Semitism has once again topped the political agenda in the wake of jihadist attacks in Paris in January, which included a deadly siege at a Jewish supermarket.
"Knowledge of history doesn't protect us from the worst... anti-Semitism and racism still exist," said Hollande in Natzwiller, site of the Struthof camp where around 50,000 were imprisoned, including many resistance fighters from across the continent.
"We must act... to protect those who may till be victims today," he added, evoking the thousands of migrants attempting the perilous journey across the Mediterranean to reach Europe from Africa and the Middle East.
The EU's president Donald Tusk, parliamentary leader Martin Schulz and Latvian Prime Minister Laimdota Straujuma were among those who attended the ceremony with Hollande.
Speaking earlier at a memorial visit in Paris, French Prime Minister Manuel Valls said: "The fight against barbarity has not ended. Without forgetting the past, we must continue the fight of our elders."
Back in Bergen-Belsen, there is little left of the Nazi camp, torched by British troops shortly after it was liberated on April 15, 1945 to prevent the spread of deadly diseases.
Susanna Christiansen, 82, who survived the camp but whose father died three days after the liberation, told news agency DPA it was overwhelming to return.
"I feel emptiness, pain and sadness."