Princess Diana Donald Trump
Princess Diana could have been the next First Lady of the US if things had just worked out differently... Reuters/Getty Images

Princess Diana's brother has refuted claims made by Donald Trump involving the late British royal.

On Wednesday, Charles Spencer took to Twitter to defend Princess Diana, by sharing his late sister's opinion of the former U.S. President following his recent remarks.

Trump had alleged that Diana was among the celebrities who "kissed" his "a**" before he went into politics. The 58-year-old also accused Trump of using Diana's name to 'sell some real estate'.

"Surprised to hear that Donald Trump is apparently claiming that my late sister Diana wanted to 'kiss his ar**', since the one time she mentioned him to me - when he was using her good name to sell some real estate in New York - she clearly viewed him as worse than an anal fissure," Charles said on social media.

Donald Trump had made a comment while promoting his new book known as "Letters to Trump" on Tuesday. The book which is set to release in April will feature 150 letters from world-renowned personalities such as Princess Diana, Queen Elizabeth, Kim Jong-un, Vladimir Putin, Oprah Winfrey, Barack Obama, Ronald Reagan, and more.

He said that the correspondence will showcase "how differently a lot of people treated" Trump before the 78-year-old ran for president.

"I think they're going to see a very fascinating life," he told Breitbart News.

"I knew them all — and every one of them kissed my a**, and now I only have half of them kissing my a**," Trump said while talking about what readers can expect in his upcoming book.

Donald Trump has mentioned Princess Diana several times in the past

The former President, who is known for making insensitive remarks, had spoken about Princess Diana many times in the past.

In an interview with Howard Stern in 1997, Trump said that he "could have" had sex with the late British royal.

In an interview, which acquired popularity once more a decade later, "The Howard Stern Show" presenter asked Trump "Why do people think it's egotistical of you to say you could've gotten with Lady Di? You could've gotten her, right? You could've nailed her?"

To which Trump had replied with "I think I could have."

In 2000, during an interview with Stern, Trump had referenced the late British royal again where he was asked if he would sleep with Princess Diana.

Trump told the host that he would have slept with Diana "without even hesitation."

"I think she's magnificent. Lady Di was truly a woman with great beauty. I've seen her a couple of times. She was really beautiful, and people didn't realise that beautiful," he said while adding that Diana was "supermodel beautiful."

"She had the height, she had the beauty, she had the skin, the whole thing."

Trump had 'aggressively' pursued Diana after her divorce in 1996

Former British TV anchor Selina Scott wrote in a 2015 column in the The Sunday Times that Trump saw Diana as "the ultimate trophy wife." She added that he had tried to woo her after her divorce from then-Prince Charles in 1996 by sending huge bouquets to the newly single princess's London home at Kensington Palace.

"As the roses and orchids piled up at her apartment she became increasingly concerned about what she should do. It had begun to feel as if Trump was stalking her," Scott wrote, adding that Diana asked the former TV anchor, "What am I going to do? He gives me the shivers."

In Trump's book "The Art of the Comeback," which released in 1997, the same year Princess Diana passed away in a car crash, he wrote "I only have one regret in the women department – that I never had the opportunity to court Lady Diana Spencer."

"She lit up the room with her charm, her presence. She was a genuine princess – a dream lady," he wrote.

Princess Diana had 'rebuffed' Trump's romantic advances

According the book, "The King: The Life of Charles III," by Christopher Andersen, Diana had 'rebuffed' Trump's advances.

The book which was published last year detailed how Trump 'aggressively pursued' Diana after her divorce from then-Prince Charles in 1996.

Meanwhile, Trump's new book, "Letters To Trump," is slated to release on April 25, 2023 and will be available for $99 (£83), with an additional option to get a signed edition for $399 (£334).