She embraced him, thanked him, held his hand and forgave him.

Holocaust survivor Eva Kor had waited 70 years for a moment such as this – and now, at last, she was face to face with a former SS man on trial for his alleged part in the slaughter at Auschwitz.

Oskar Groening looked startled at first, then smiled. He placed a kiss on her cheek and listened to the words of the 81-year-old woman who, with her twin sister, was once the subject of Josef Mengele’s monstrous human experiments.

Embrace: Seventy years after Auschwitz was liberated, Eva Kor embraces former Nazi guard Oskar Groening

Redemption: Holocaust survivor Kor takes the hand of Groening as he stands in the dock accused of complicity to murder 300,000 people

Auschwitz survivor Eva Kor has spoken of how infamous Josef Mengele stood over her bed and laughed after she was injected with a 'deadly germ'

Groening (pictured) described in chilling detail Wednesday how cattle cars full of Jews were brought to the Auschwitz death camp, the people stripped of their belongings and then most led directly into gas chambers

Groening, who worked for an insurance company after the war, has testified as a witness in other Nazi trials

The extraordinary moment of reconciliation took place as the 93-year-old former death camp clerk – known as the Bookkeeper of Auschwitz – prepared to listen to Mrs Kor’s evidence in a trial that could condemn him to die in jail. She claims Groening was so overwhelmed by her unexpected gesture that he fainted.

Mrs Kor was criticised by other victims and their families for her public forgiveness. ‘Not only criticism,’ she said. ‘They called me a traitor.’

But she explained: ‘As long as we understand my forgiveness that the victim has a right to be free, you cannot be free from what was done to you unless you remove from your shoulder the daily burden of pain and anger and forgive the Nazis – not because they deserve it, but because I deserve it.

‘When I talk to survivors, and I say why on earth does my forgiveness hurt you, they have no answers. I guess victims like to have more victims; the bigger the crowd, the better. I don’t understand it.

‘The victims, 70 years after liberation, with 300 others, they were all talking about their experience, falling apart – “poor me… what have they done to me?”

‘I don’t forget what they have done to me. But I am not a poor person – I am a victorious woman who has been able to rise above the pain and forgive the Nazis.’ When she approached him before the hearing, she held her arms outstretched towards his – and this most unlikely pair became locked in an embrace.

Recovery: Miriam and Eva Kor as shown in a 1949 photo. Eva Kor and her twin sister Miriam were among the 1,500 twins (amounting to 3,000 children) Dr. Josef Mengele experimented on in Auschwitz

SS Sergeant Oskar Groening is on trial charged with complicity in the killing of 300,000 Jews at the Nazi extermination camp

Asked yesterday why she had hugged him, she said it had not been planned and added: ‘I wanted to thank him for having some human decency in accepting responsibility for what he has done.

‘I was always interested in meeting him face to face because I believe that there is a human interaction that I cannot predict and no one else can predict.’

Mrs Kor later tweeted: ‘I met Oskar Groening, introduced myself reached to shake his hand-he grabbed my arm & fainted-I screamed 4 help. It was a strange reaction!!’

She said Groening bore responsibility for helping to run the wartime concentration camp – but urged him to spend his last days teaching others about the evil of Nazism.

In a moving interview on BBC Radio 4’s Today programme she continued: ‘He is 93 years old. Putting him in jail is absurd. But he can do some good…’

Mrs Kor travelled more than 4,000 miles from home in Indiana, US, to the hearing in Luneburg, Germany.

Groening was known as the 'Bookkeeper of Auschwitz' because it was his responsibility to collate and ship the valuables of the doomed back to the SS in Berlin

Josef Mengele (1911-1979), the notorious Nazi German physician, in an image taken from from Nazi Hunter: The Wiesenthal File, by Alan Levy

Her family had been among hundreds of thousands deported in cattle trucks from Hungary and Romania to death camps such as Auschwitz.

Groening’s job at the camp was to collect and tally money stolen from the new arrivals and then send it to Berlin. He denies being an accessory to the murder of at least 300,000 Jews there but has begged forgiveness for what he called his ‘moral guilt’.

It was at the camp that the ten-year-old Eva and her twin sister Miriam were singled out by Mengele for his grotesque genetic experiments.

Being chosen ‘didn’t mean the person was assured a life’, she said. ‘It meant you were not immediately taken to the gas chamber.’ She told how she had to stay alive for the sake of her twin sister. She knew if she had died, it would effectively sentence her sister to death – one twin without the other would have been useless for the experiments.

Survivors from Auschwitz (pictured), who are plaintiffs in the case, travelled from the United States, Canada, Hungary and elsewhere to attend Groening's trial

Between May 16 and July 11, 1944, Groening was on duty when 450,000 Hungarian Jews were transported there, with 300,000 being gassed just after arrival. Pictured, Auschwitz survivors

She said: ‘She would have been killed immediately, and Mengele would have done comparative autopsies. So I spoiled their experiment. I survived.’ Mengele used 1,500 sets of twins in his experiments, and only an estimated 180 to 250 individuals survived.

Mrs Kor described how she was injected with a ‘deadly germ’ that she still cannot identify. ‘Mengele stood by my bed and was laughing sarcastically after reading my fever charts and saying I had only two weeks to live. For those following two weeks I have only one single memory: crawling on the barrack floor and trying to reach a faucet (tap) at the other end of the barrack for some water.

‘As I was crawling and fading out of consciousness, I kept saying to myself, “I must survive”. And I did.’

Mrs Kor said she asked the defendant if he knew Mengele. ‘He told me no.’ She also asked if he knew what happened to the files Mengele kept on the twins he subjected to experiments. Those files, she said, ‘have disappeared from the face of the earth’.

She added: ‘I still don’t know what was injected into my body, and I don’t know what was injected into my twin sister’s body, who died 20 years ago, nor into the bodies of any of the other twins.’

Appealing for any information about the files, she said Miriam’s kidney failed in 1987 and although she donated one of her own, Miriam subsequently died.

‘I believe in this big world we have talked so much about human rights that I should have the human right to find out what they injected into me 70 years ago.’