More than 200 survivors gathered at the former Nazi extermination camp of Auschwitz, many probably for the final time, to commemorate the 75th anniversary of its liberation.

As rows over the make-up of the international guest list at the memorial ceremony threatened to overshadow Monday’s event, survivors who drew on harrowing memories of their incarceration warned the lessons from the atrocities sanctioned by Adolf Hitler’s administration and carried out often by ordinary Germans were in danger of being forgotten.

“The Holocaust was sponsored and was okayed by a government. Not only did they allow it to happen but they enforced it and encouraged regular people to become killers,” said Benjamin Lesser, a 92-year-old Polish-born Jew whose family was sent to Auschwitz in 1944. More than 1.1 million people were murdered at the camp, most of them Jews.

“I have returned so that I don’t forget any of the details of what happened to me, so I can keep the memories alive, and stop the world from acquiring amnesia,” he added, emphasising widespread concern over the rise in antisemitic attacks, in particular in Europe and North America.

Quick guide What happened at Auschwitz? Show Hide The Auschwitz concentration camp complex in south-west Poland was the site of the largest mass murder in a single location in human history. While precise numbers are still debated, according to the US Holocaust Memorial Museum, the German SS systematically killed at least 960,000 of the 1.1-1.3 million Jews deported to the camp. More people died at Auschwitz than at any other Nazi concentration camp. When the camp was liberated on 27 January 1945, Soviet troops found grisly evidence of the horror. About 7,000 starving prisoners were found alive, and millions of items of clothing that once belonged to men, women and children were discovered along with 6,350kg of human hair. In January 1942, the Nazi party had decided to roll out the “Final Solution”. Camps dedicated solely to the extermination of Jews had been created before, but this was formalised by SS Lieut-Gen Reinhard Heydrich in a speech at the Wannsee conference. The extermination camp Auschwitz II was opened in the same year. Auschwitz II had the largest prisoner population of any of the three main camps on the site. In January 1942, the first chamber using lethal Zyklon B gas was built. Four further chambers were built, and these were used for systematic genocide up until November 1944. Auschwitz was also the site of disturbing medical experimentation on Jewish and Roma prisoners, including practices such as castration and sterilisation. SS captain Dr Josef Mengele was one of the physicians practising there. More than 7,000 Nazi personnel are thought to have served at Auschwitz but only a few hundred have been prosecuted for the crimes committed there. The pursuit of justice has not ceased, with German justice officials saying in 2013 that there were 30 surviving Auschwitz officials who should face prosecution. In 2019, a former guard at Stutthof concentration camp was placed on trial. George Arnett

Presidents, prime ministers and royalty from around the world attended the commemorations, but not top world leaders, who visited Yad Vashem in Jerusalem earlier this week for another high-profile anniversary event.

Ronald Lauder, the president of the World Jewish Congress (WJC), which has funded the return of more than 100 survivors and their families, said: “The emphasis here is on the survivors, as it should be, not on political leaders. There will probably not be another major anniversary as we’re losing so many of them.”

The survivors in attendance are aged between 75 – a woman who was born in the camp – and 101. They have travelled from all over the world, mainly North America and across Europe, Israel, South and Central America and Australia. A team of 50 therapists and medics were on hand to attend to the survivors and their also often elderly offspring.

Facebook Twitter Pinterest David Lenga was 17 when he entered the camp in 1944. Photograph: Wojtek Radwański/AFP via Getty Images

At a dinner on Sunday held in a former tram depot in Kraków’s Jewish quarter, about 700 survivors and their families gathered to celebrate a revival of Jewish life around the world.

An unexpected guest, the Ukrainian president, Volodymyr Zelenskiy, who is Jewish and lost members of his family in the Holocaust, told the gathering the world should learn about humanity from the survivors whose stories of endurance and forgiveness were exemplary.

“You are truly amazing. You are strong and incredibly courageous. So you are an example that we should follow … The Holocaust is called the dark period in the history of humanity and you are the rays of sunshine that penetrated that darkness.”

'I see it as a chance to finally say goodbye': Auschwitz survivors tell their stories Read more

David Lenga, 92, from Los Angeles, was among about 20 survivors who returned to Auschwitz on Sunday, walking silently through the notorious entrance gate bearing the words Arbeit macht frei (work sets you free) on a cold, sunny morning, taking his daughter Berta Kaplowitz with him for the first time on a tour of his former prison.

Lenga, who was 17 when he entered the camp in summer 1944, survived in part by making woollen jackets for SS guards out of camp blankets, for which he received extra food rations. He later went on to become a successful tailor in Beverly Hills. He said he had refused to let the Holocaust define his life, despite the fact it claimed 98 members of his family, with him and his father the only two to survive.

“I wanted to be better than that,” he said. “I’ve let my past go and concentrated instead on being a role model for my family, and have been helped by being blessed with a wonderful marriage, three beautiful daughters, seven grandchildren and 16 great grandchildren.”

Angela Orosz, 75, from Montreal, stood in front of the former red-brick barracks and recalled her mother’s account of giving birth to her in secret on a top bunk in Auschwitz-Birkenau in December 1944.

“I have little choice but to come back, as the youngest survivor,” she said, clutching a bright pink shawl around her shoulders. “I grew up looking at photographs of relatives, and when I asked about them was told “he’s dead, she’s dead”. When I was older they told me the truth, that they had been murdered.

Facebook Twitter Pinterest Angela Orosz visits the memorial site. ‘I have little choice but to come back’ Photograph: Wojtek Radwański/AFP via Getty Images

“I always claimed to my kids that I had suffered no trauma from having been here, until my daughter asked me why then, unlike other families, did I never throw potato peelings away? Because my mother had probably survived because of the peelings she had eaten and the goodness in them, she had been able to give birth to me and so I had survived, so of course the survival instinct I inherited from her made me always do the same.”