Aviva Bar-On performed a song she had been coaxed by Professor Francesco Lotoro to recall from more than 70 years earlier whilst in Theresienstadt concentration camp in the former Czechoslovakia.

It had been composed by Ilse Weber, a nurse in the camp, who eventually perished at Auschwitz.

It was the first time the song had been performed in public and was one of 11 heard during JNF UK’s Notes of Hope concert in Israel’s capital.

It was the highlight of Lotoro’s 30-year search for scores and lyrics composed by talented professional and amateur musicians during their darkest hours in Nazi camps.

Lotoro, 54, a composer and pianist, has thus far salvaged and recorded 8,000 songs, symphonies and operas by camp inmates, not all Jewish.

But he knows he is in a race against time as some material is thrown out by those not realising its value, or merely suffers the ravages of time and deteriorating.

He has also relied on the few survivors like Aviva, who were able to recall music and words perfectly.

Lotoro has found material in bookshops, attics and archives, but admits: “There are more than 10,000 more waiting to be deciphered that I have not yet touched.”

Aviva was nine when she was transported to Theresienstadt.

When she became ill, she found herself in the so-called children’s hospital there, cared for by Ilse Weber.

Ilse entertained the children on the mandolin, singing her own compositions.

“She was such a wonderful, nice, smiling lady,” recalled Aviva.

“She sang very nicely and after I recovered I asked her permission to come and hear the songs and I think I am the only one in the world that remembers them.

“I remember her music very well.”

Some of the songs were amusing, about diarrhoea and jaundice.

Sunday’s audience heard her perform When I Was Lying Down, which refers to having “A nasty illness — let’s shove a plug in it”.

“I feel I am the voice. I am happy. Nobody knows the songs except me, I’m not sure whether I am happy or proud,” said Aviva who now lives in Israel.

“When I sing them it is emotionally hard for me.”

After the war a small book of Ilse’s poetry was discovered.

Recalling her three years in Theresienstadt, Aviva said: “People wanted always to be optimistic.

“They were always looking for some hope, something positive, because life was terrible.

“There were so many deaths and horrible things and hunger. When I say it, I have no words.”

She added: “The life of music in Terezin was very, very rich. They came from the Czech Republic and also from Germany. There were a lot of performers there.

“There were opera singers. They created some operas. They had no notes, [they learned them] by heart.

“I don’t know how they did it but there were a lot of performances of opera in Terezin and there was also a musician who created a women’s choir.

“I was the only child in his choir. I was very proud. There were a lot of people who were highly educated.”

On Sunday, 19 children from two music academies in Israel’s Negev region joined the Ashdod Symphony Orchestra, conducted by Lotoro, to perform in Jerusalem.

They had been coached by Lotoro who, at the age of 15, felt the pull of Judaism, having been raised as a Catholic.

He eventually converted to Judaism in 2004, discovering later that he was descended from a family that had been forcibly converted to Christianity.

He cannot recall precisely when his obsession with collecting the music of the Holocaust began, but over three decades he has discovered music that was written in notebooks, on coal sacks, food wrappers, “very little tickets”, toilet paper, x-rays, telegrams and postage stamps.

Some music and lyrics were retrieved from the ageing memories of camp survivors, many now in their eighties and nineties, and others no loner alive.

Lotoro’s period of research extended to include material from 1933 when Dachau opened until the death of Stalin in 1953.

Lotoro has collected material also from Roma, Christians, political prisoners, homosexuals and others. He said: “As Jews we have other duties. The Torah says, ‘Be a light unto the nations’.

“We have to be a role model for others. The Roma did not record the music they created in the camps. It took a Jew to record their music and that of all the others.

“For us, preserving the memory is not optional, it’s a mitzva, a precept. And memory is universal, not just Jewish.”

In the audience on Sunday was Alan Ehrlich, nephew of famed Berlin entertainer Max Ehrlich who perished during the Holocaust after having been incarcerated in Westerbork transit camp.

Alan, born seven months after Max’s death, said: “The camp commandant Conrad Geneker was stage-struck by all these showbiz celebrities.

“There was my uncle Max, Willy Rosen, Erich Ziegler, Franz Engel and many more.

“Suddenly the best cabaret in Europe was to be found in Westerbork.

“SS officers would come to watch in the front rows with the Jews sitting behind them.

“Their music became Westerbork hits, with prisoners constantly humming their tunes.

“In the camps, there was an explosion of creativity,” he said. “When your life is in danger, you create more as a testament for the future.”

Alan addresses Lotoro reverentially as “maestro”. Among works performed on Sunday was Tango in Auschwitz, written by 12-year-old Irka Janowski.

Samuel Hayek, chairman of JNF UK, said: “I was moved to tears by the music. To be a respected and valued person in a community, then stripped of your humanity and dignity, to be hungry and beaten, to not know where your loved ones are, and then to sing.”

He hoped that the concert could be brought to London and did not rule out the possibility of a Manchester date, too.

Israeli defence minister, Avigdor Lieberman, was present, deputising for Prime Minister Benjamin Netanyahu who pulled out at the last minute over security fears.