A senior member of the British royal household resigned Wednesday for repeatedly asking a black charity campaigner where she was "really" from.
Ngozi Fulani, the chief executive of the London-based Sistah Spacel group, was attending a reception at Buckingham Palace with other campaigners on Tuesday.
After saying she was born and raised in the UK, and was British, Fulani said "Lady SH" asked her: "Where do you really come from, where do your people come from?"
She was then asked: "When did you first come here?"
The palace described the comments as "unacceptable and deeply regrettable".
"We have reached out to Ngozi Fulani on this matter, and are inviting her to discuss all elements of her experience in person if she wishes," a statement read.
"In the meantime, the individual concerned would like to express her profound apologies for the hurt caused and has stepped aside from her honorary role with immediate effect.
The late Queen's lady-in-waiting Susan Hussey who is also a godmother to Prince William was named by UK media as the woman in question.
William and Kate head to US
A spokesperson for William said that it was "really disappointing" to hear about the experiences.
"The comments were unacceptable, and it is right that the individual has stepped aside with immediate effect," the Kensington Palace spokesperson said.
The incident threatens to cloud the Prince and Princess of Wales, William and Kate's first visit in eight years to the United States.
They are in Boston to award the Earthshot Prize for initiatives to tackle climate change.
Last year, William insisted "we are very much not a racist family", after his estranged brother Prince Harry and sister-in-law, Meghan made allegations of racism in the Royal family.
Meghan, in the interview, said one unnamed member of the family had asked, before their son Archie was born, how dark his skin might be.
The palace was earlier this year accused of being tone deaf to calls from Caribbean countries which still have King Charles as head of state to acknowledge Britain's past role in slavery.
William and Kate's visit to Jamaica was also criticised for smacking of colonialism.
lo/jcg (AP, AFP, Reuters)