Three Holocaust survivors have recalled the “living hell” they endured at Auschwitz as they prepared to give evidence at the trial of one of the infamous Nazi death camp’s last remaining SS guards who is accused of complicity in the murder of 170,000 prisoners.

The 94-year-old Reinhold Hanning will appear before judges in the German city of Detmold on Thursday accused of being part of what prosecutors have described as the “Auschwitz murder machine”, which slaughtered 1.1 million Holocaust victims during the Second World War. He has denied involvement in murder.

But three former Auschwitz inmates have spoken of the horror of the death camp and underlined prosecutors’ claims that anyone who was a guard there was automatically complicit in mass murder.

Half-Jewish Erna de Vries, 93, was 19 when her mother was sent to her death in the Auschwitz gas chambers.

Shaking with emotion, she told reporters: “I was certain I was going to suffer the same fate.

“I was sent to the camp death block where everyone was waiting to be gassed.”

Former SS guard Reinhold Hanning faces trial this week

She added: “It was stinking, grossly overcrowded and full of overflowing buckets of excrement. All I wanted was to see the sun before I died.”

Ms de Vries said she only survived because the Nazis had decided at the last minute that half-Jewish prisoners should do forced labour instead of being sent to their deaths. “I have very mixed feelings about seeing a former camp guard,” she admitted.

Berliner Leon Schwarzbaum recalled how he saw truckloads of naked Auschwitz prisoners being driven screaming towards the gas chambers. “It was a living hell, the unbearable smell of burning flesh was ever present. The flames from the crematorium chimneys were huge,” the 95-year-old said. Mr Schwarzbaum managed to survive by being selected for work outside the camp.

Justin Sonder, now 90, was 16 when he arrived in Auschwitz. He was operated on without anaesthetic by camp doctors, who cynically painted an iodine swastika on his knee. “After the operation, I was convinced I would be considered unfit and useless and sent to the gas chambers,” he said “I owe my survival to the doctor who did not put my name forward,” he added.

Mr Sonder said he was convinced it was “absolutely right” to put 94-year-old Mr Hanning on trial. “It is never too late to bring the perpetrators to justice. There was no such thing as a harmless SS man,” he insisted.