'Swan Song': New book by Princess Diana's brother drops

Charles Spencer's book about his late sister Princess Diana's life and former marriage to Britain's now King Charles III hit bookstores on Tuesday.

The book titled  "Swan Song: Diana, My Sister" is being published globally by Penguin and has been translated into 12 languages.

The memoir triggered a royal row even before it went on sale, after some of its pre-published extracts —  laden with Spencer's explosive claims  —  received a rare reaction and rebuttal from the king.

Charles Spencer, the 9th Earl Spencer, is Diana's younger brother and has long clashed with the royal House of Windsor over how they treated the princess.

What does Charles Spencer say in his memoir of Princess Diana?

In one of the claims that made a splash ahead the new book's release, Spencer accused Charles of sounding "giddily elated" and "like a lottery winner" when he had called him after Diana's death.

Spencer also writes that he had argued against plans for Charles and Diana's sons, William and Harry, to walk in their mother's funeral procession in 1997, saying that she would not have wanted them to go through that ordeal.

Spencer claims Charles "went ballistic" during the argument , telling him: "Rest assured, we'll forget her soon enough."

William was 15-years-old at the time and Harry was 12.

The world was moved by somber visuals of the young princes walking behind Diana's coffin.

How has King Charles III reacted to Spencer's claims?

Following the release of the book's excerpts last week, Buckingham Palace published a strongly-worded statement.

"His Majesty is mindful that the pain of fraternal grief can cloud reason, affect judgement and color memory in ways others do not recognize, even many years after such a loss," it said in a statement considered rare as far as responses from the royal household go.

Princess Diana's life and death

In 1981, a 20-year-old Lady Diana Spencer married a 32-year-old Charles, who was then the Prince of Wales, in a fairytale wedding that was televised globally.

Their whirlwind romance soon hit rock bottom and culminated in a public breakdown of their marriage. Diana famously told the BBC in an interview that "there were three of us in this marriage, so it was a bit crowded" in reference to Charles' ⁠relationship with Camilla Parker ​Bowles.

Diana, known as the people's princess, was loved by people from all over the world. Her popularity led to her experiencing a media frenzy that lasted nearly all her adult life.

The royal couple divorced in 1996 and Diana died a year later, aged 36, in a car crash in Paris as she was being pursued by paparazzi.