The Duke and Duchess of Cambridge have joined genocide survivors to light candles at an International Holocaust Memorial Day event in London.
The royals, Prime Minister Boris Johnson and faith leaders attended the service in Westminster, to mark 75 years since Auschwitz was liberated.
The duke gave a reading and the couple spoke to survivors of the Holocaust and more recent genocides.
It came as dozens of world leaders met at Auschwitz in Poland.
They joined around 200 Holocaust survivors – including some who are now living in the UK – who returned to the former Nazi death camp for a commemoration.
Batsheva Dagan, who was given the number 45054 on arrival at Auschwitz, told those gathered in Poland that “human dignity did not belong” at the camp.
“Quite the opposite,” she said. “Human dignity was trampled.”
At Central Hall in Westminster, those taking part included Archbishop of Canterbury Justin Welby and the Chief Rabbi, Ephraim Mirvis.
Prince William paid tribute to his great-grandmother Princess Alice, who he said risked her own life to save a Jewish family – the Cohens – in 1943.
Alice’s bravery was recognised by Israel which in 1993 posthumously bestowed the title of Righteous Among the Nations on her.
Reading from a letter written by a friend of the princess, Prince William said: “The princess put a small two-room apartment on the third floor at the disposal of Mrs Cohen and her daughter.
“It was thanks to the courageous rescue of Princess Alice that the members of the Cohen family were saved.
“The members of the Cohen family left the residence three weeks after liberation, aware that by virtue of the princess’s generosity and bravery had spared them from the Nazis.”
The Duchess of Cambridge later praised survivors and their relatives for sharing their “heartbreaking” stories at the event and she said she and William found the ceremony “very poignant”.
Mr Johnson told those listening he felt a “deep sense of shame” that anti-Semitism continued in the UK today.
The PM said Britain seemed “to be dealing with a resurgence of the virus of anti-Semitism”, saying: “I know that I carry a responsibility as prime minister to do everything possible to stamp it out.”
He vowed to ensure the horrors of the Holocaust were not forgotten and lent his support to the proposed National Holocaust Memorial and Education Centre near Parliament.
“As prime minister I promise that we will preserve this truth forever,” he said.
The UK commemoration in Westminster honoured survivors of the Holocaust – also known as the Shoah, in which millions of Jewish people were killed – Nazi persecution, and the genocides which followed in Cambodia, Rwanda, Bosnia and Darfur, according to organisers.
Around one million people – many of them Jewish – were killed at Auschwitz before it was liberated by the Russian army on 27 January 1945.
Earlier, two portraits of Holocaust survivors taken by the Duchess of Cambridge for an upcoming exhibition were released to mark the anniversary of the liberation of Auschwitz.
The UK Holocaust Memorial Day commemorative event is airing on BBC Two from 1900 GMT and will be available on the BBC iPlayer.