Seventy years after the slaughter of some 300,000 people, including her family, Holocaust survivor Eva Kor recently met face-to-face with a former SS officer who was one of those responsible for helping run the so-called Nazi death camp.

But instead of getting her revenge, Kor embraced him, kissed him on the cheek, thanked him and forgave him for his past mistakes.

''I believe forgiveness is such a powerful thing... And this is what our world desperately needs besides punishment,'' Kor said in a new Channel 4 documentary that was aired Saturday night, the Daily Mail reported.

The 81-year-old woman attended a court hearing in Germany as one of the witnesses for the trial of Oskar Groening, known as the Bookkeeper of Auschwitz, who was charged with assisting in the war crimes during his two years at the camp. Groening is now 93 years old.

She and her twin sister Miriam, both Hungarian Jews, were among the subjects of Josef Mengele's monstrous human experiments at Auschwitz concentration camp in attempts to develop genetic techniques for Hitler's dream of creating a "pure'' Aryan race. At least 1,500 sets of twins were used in the experiments by Mengele, who earned the nickname "Angel of Death."

Kor's mother, father and two older sisters were gassed to death in the camp. Miriam died in 1993.

In the documentary, "The Girl Who Forgave the Nazis," Kor shared her painful ordeal at the death camp and how she and her twin sister survived it.

In one of those incidents inside the camp, she said the Nazis took them away from their mother upon learning they were twins. "My mother was screaming, and I remember her hand was still in the air and she was crying and I never even got to say goodbye to her. I didn't realise at that moment that would be the last time I would ever see her for the rest of my life," she said.

Kor said she saw bodies including those of children everywhere then. ''At that moment I made a pledge to myself that I would do anything and everything within my power to make sure Miriam and I shall not end up on the filthy latrine floor.''

Today, Kor said she found compassion in her heart to forgive his tormentors. She even unofficially adopted the grandson of SS commander Rudolf Hoess, who oversaw the murder of more than 1 million people at Auschwitz, said the Mail.

She said she used to react as a victim by harbouring anger in her heart until she found "forgiveness," which helped her release the pressure of anger and accept compassion instead.

Kor, who now lives in the U.S., even thanked Groening "for having some human decency in accepting responsibility for what he has done.''

She appealed to Groening to spend his remaining days making statements and teaching others about the evil of Nazism "to make up for his bad job.''

"He is 93 years old. Putting him in jail is absurd. But he can do some good,'' she said in an interview on BBC Radio 4's Today programme.

Kor also called for an end to the prosecution of former SS officers.