Meghan Markle says a "calculated smear campaign" is being carried out against her by royal aides ahead of her interview with Oprah Winfrey.
The rebuttal comes after The Times reported allegations that the Duchess of Sussex had bullied two palace staff members, leading to them quitting their jobs.
The newspaper said former communications assistant Jason Knauf submitted a complaint in 2018 to protect workers who were allegedly coming under pressure from the former actress.
Meghan, 39, denies the claims - which have emerged just days before her and husband Prince Harry 's interview with Oprah, 67, is set to be screened.
And her spokesperson told The Sun today: "Let's just call this what it is - a calculated smear campaign based on misleading and harmful misinformation.
"We are disappointed to see this defamatory portrayal of The Duchess of Sussex given credibility by a media outlet.
"It's no coincidence that distorted several-year-old accusations aimed at undermining The Duchess are being briefed to the British media shortly before she and The Duke are due to speak openly and honestly about their experience of recent years.
"In a detailed legal letter of rebuttal to The Times, we have addressed these defamatory claims in full, including spurious allegations regarding the use of gifts loaned to The Duchess by The Crown.
"The Duchess is saddened by this latest attack on her character, particularly as someone who has been the target of bullying herself and is deeply committed to supporting those who have experienced pain and trauma.
"She is determined to continue her work building compassion around the world and will keep striving to set an example for doing what is right and doing what is good."
The "spurious allegations" relate to claims that Meghan wore earrings gifted by Prince Mohammad bin Salman weeks after the death of Jamal Khashoggi.
A US intelligence report published last week said the Saudi Arabian royal approved the mission to capture or kill the journalist.
The bullying allegations stem from claims there was a tense atmosphere when Meghan was a working royal, which drove some staff to tears.
Two senior members of staff claim that they were bullied by the duchess, according to the Times, and another former employee has allegedly claimed they had been personally "humiliated" by Meghan.
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According to the newspaper, a complaint was allegedly submitted in October 2018 by Jason Knauf, then the couple’s communications secretary.
It is alleged Harry, 36, personally intervened and "pleaded with Knauf not to pursue it", a source told the newspaper.
A spokesman for the couple said Harry would not interfere in staff matters.
Meghan and the prince's interview with television icon Oprah will be screened on CBS this Sunday, March 7.
It is thought that the pair will discuss their departure from the royal family and Britain, among a wide range of other issues.
Some critics have suggested that the interview should be postponed amid Prince Philip's ongoing health issues.
The Duke of Edinburgh, 99, has been in hospital for more than two weeks, having moved facility on Monday.
The Mirror has contacted Buckingham Palace for comment.