King Charles responds to criticisms in upcoming book of Princess Diana's brother

Britain's King Charles took the unusual step on Wednesday of responding to criticism by the brother of his late first wife Diana, saying via a spokesperson that grief could impact reason, judgment and memory.

The assertions, made in a soon-to-be published book, relate to the now-monarch's conduct in the days after Diana's death in 1997.

Diana was killed at the age of 36 when the car carrying her and her lover Dodi al-Fayed crashed in Paris as it sped away from chasing paparazzi photographers on motorbikes.

Her brother, Charles Spencer, alleges in a soon-to-be-published memoir that the then-Prince Charles told him "rest assured, we'll forget her soon enough", according to a report in the Daily Mail, which begins serialising the book on Thursday.

The reported comments were made in an argument over whether Diana and Charles' children, princes William and Harry, should walk behind her coffin during her funeral — something Spencer objected to, the report said.

Diana became the most photographed woman in the world after marrying Charles in a glittering ceremony in 1981. However, the marriage turned sour and the couple eventually divorced in 1996.

Asked about the report, a Buckingham Palace spokesperson said: "While we do not comment on books as a matter of principle, His Majesty is mindful that the pain of fraternal grief can cloud reason, affect judgment and colour memory in ways others do not recognise, even many years after such a loss."

Prior to the book's release, Spencer said: "The aim of this book is to tell the truth about Diana from her brother's perspective ... I want to speak on Diana's behalf and do so in an openly positive way."

-Reporting by Michael Holden, writing by William James, Editing by Rosalba O'Brien/Reuters