The Prince of Wales spoke of the “deeply worrying growth of fake news” as he urged people to challenge those who peddle unfounded conspiracy theories on Holocaust Memorial Day (HMD).

Charles, who is patron of the HMD Trust, spoke of the need to “be the light in the darkness” as people across the country placed candles in their windows, and national landmarks turned purple for the evening in recognition of genocide.

Speaking during an online-only HMD ceremony on Wednesday night to reflect on the millions of Jews and other minorities killed in concentration camps in the Second World War, Charles said people “must remember” the “inspiring heroism” of those who survived persecution by the Nazis.

But he also warned: “We have also seen reckless assaults on the truth and the deeply worrying growth of fake news and of irrational theories, not grounded in reality but rooted in dark places of hatred and fear.

“We have seen reason rejected, objectivity abandoned, history discounted – even the Holocaust denied.”

He added: “As I speak, the last generation of living witnesses is tragically passing from this world, so the task of bearing witness falls to us.

“This is our time when we can, each in our own way, be the light that ensures the darkness can never return.”

The Duchess of Cambridge, Premier League footballers and the Prime Minister were among those to support the day of remembrance, with Boris Johnson one of several political leaders reading lines from a poem broadcast at the ceremony.

Mr Johnson also described the testimonies of a concentration camp survivor and a British soldier who helped liberate Bergen-Belsen as “perhaps the most powerful things I have ever heard” in a video call from Downing Street.

Earlier, the Duchess of Cambridge was visibly moved during an online chat with two concentration camp survivors, telling them their “dedication in educating the next generation, the younger generations, about your experiences and the horrors of the Holocaust shows extreme strength and such bravery in doing so, it’s so important and so inspirational”.

Pre-recorded messages from Premier League footballers Jordan Henderson and Bruno Fernandes, and contributions from religious leaders and celebrities including adventurer Bear Grylls, also featured in the online service.

This year’s theme – being the light in the darkness – was decided 18 months ago, but the global coronavirus pandemic, which has seen deaths, ill-health, economic ruin, school closures and mental health problems, means it has taken on added resonance.

For more information visit www.hmd.org.uk.