Anne Frank Trust's Instagram on Monday shared King Charles and Queen Camilla's photos withEva Schloss who died aged 96 on Sunday.
The pictures of the king and his wife withAnne Frank's step-sister were also reposted to Instagram Stories of the Royal Family account.
"These photos capture just a small part of her extraordinary work empowering young people to challenge prejudice," the organization's statement accompanying the pictures said.
On Sunday, King Charles led tributes to Eva Schloss, who the co-founder and honorary president of the Anne Frank Trust, which Queen Camilla is Patron of.
In a tribute posted on social media, the King wrote: "My wife and I are greatly saddened to hear of the death of Eva Schloss."
He continued: "The horrors that she endured as a young woman are impossible to comprehend and yet she devoted the rest of her life to overcoming hatred and prejudice, promoting kindness, courage, understanding and resilience through her tireless work for the Anne Frank Trust UK."