Image copyright Duchess of Cambridge Image caption Steven Frank is seen alongside his granddaughters Maggie and Trixie

The Duchess of Cambridge has taken photographs of Holocaust survivors in a contribution to an exhibition marking 75 years since the end of the genocide.

The duchess said her subjects were "two of the most life-affirming people that I have had the privilege to meet".

It comes as the world marks International Holocaust Memorial Day, 75 years after Auschwitz was liberated.

Later, the Duke and Duchess of Cambridge will attend the UK commemorations in Westminster.

In the images taken by Catherine for the exhibition, which opens later this year, two survivors are pictured with their grandchildren.

One of her portraits was of 84-year-old Steven Frank, originally from Amsterdam, who survived multiple concentration camps as a child.

He is pictured alongside his granddaughters Maggie and Trixie Fleet, aged 15 and 13.

Her other portrait is of 82-year-old Yvonne Bernstein, originally from Germany, who was a hidden child in France throughout most of the Holocaust.

She is pictured with her granddaughter Chloe Wright, aged 11.

Image copyright Duchess of Cambridge Image caption Yvonne Bernstein is pictured with her granddaughter Chloe Wright

Speaking about the project, the duchess, who is the patron of the Royal Photographic Society, said: "The harrowing atrocities of the Holocaust, which were caused by the most unthinkable evil, will forever lay heavy in our hearts.

"Despite unbelievable trauma at the start of their lives, Yvonne Bernstein and Steven Frank are two of the most life-affirming people that I have had the privilege to meet.

"Their stories will stay with me forever."

The exhibition will bring together 75 images of survivors and their family members; one for every year since the largest Nazi death camp, Auschwitz, was liberated on 27 January 1945.

Judith Rosenberg, Scotland's last Holocaust survivor, recalled being separated from her family and transported to the camp, where she came face to face with the murderous Nazi doctor Josef Mengele.

"There was no life. We were starving," the 97-year-old told the BBC in an interview to mark the anniversary of the camp's liberation.

Commemorations are being held around the world on Monday to mark the end of the Holocaust, in which six million Jews and millions of others were murdered, and to honour survivors of subsequent genocides in Cambodia, Rwanda, Bosnia and Darfur.

'Deeply personal'

The duchess said her aim was to make the portraits "deeply personal to Yvonne and Steven - a celebration of family and the life that they have built since they both arrived in Britain in the 1940s".

"It was a true honour to have been asked to participate in this project and I hope in some way Yvonne and Steven's memories will be kept alive as they pass the baton to the next generation," she said.

Image copyright Getty Images Image caption The Duchess of Cambridge was seen with her camera on a visit to Pakistan last year

Two more survivors were photographed by other contributors. In a photograph by Frederic Aranda, Joan Salter, 79 - who fled the Nazis as a young child - appears with her husband Martin and her daughter Shelley.

John Hajdu, 82, who survived the Budapest Ghetto, is in a portrait with his four-year-old grandson Zac, photographed by Jillian Edelstein.

The photographic project aims to inspire people across the UK to consider their own responsibility to remember and share the stories of those who endured persecution at the hands of the Nazis.

It is a collaboration between the Holocaust Memorial Day Trust, Jewish News and the Royal Photographic Society.

Catherine has been honoured for her photography and has previously shared pictures she has taken of her family.