Ahead of Oprah interview, royal aides claim Meghan Markle bullied them in 2018

Meghan, Duchess of Sussex, issued a statement defending herself after a report in The Times of London quoted unnamed palace sources accusing her of bullying staff in 2018 while living at Kensington Palace with Prince Harry.

The report in the British newspaper, which comes just days before an explosive interview between the royal couple and Oprah Winfrey is set to air, was called "a calculated smear campaign" by a spokesperson for the Duke and Duchess of Sussex on Wednesday.

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The story claims to quote a 2018 email from Jason Knauf, Harry and Meghan's former communications secretary, which was allegedly sent to a senior royal official saying that he is "very concerned that the duchess was able to bully two PAs of the household in the past year."

The email also allegedly said that "the duchess seems intent on always having someone in her sights."

NBC News has not seen the email to verify it.

"Let’s just call this what it is — a calculated smear campaign based on misleading and harmful misinformation," a spokesperson for Harry and Meghan told NBC News in a statement. "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."

On Wednesday, Buckingham Palace released a statement saying there would be an investigation into the claims made the report.

"We are clearly very concerned about allegations in The Times following claims made by former staff of The Duke and Duchess of Sussex," the palace said. "Accordingly our HR team will look into the circumstances outlined in the article. Members of staff involved at the time, including those who have left the Household, will be invited to participate to see if lessons can be learned.

"The Royal Household has had a Dignity at Work policy in place for a number of years and does not and will not tolerate bullying or harassment in the workplace."

In the interview with Winfrey, which will air in a two-hour special Sunday on CBS, the couple is expected to discuss the pressure Meghan was under before they decided to step down from their duties as senior members of the royal family last year.

"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," the statement reads. "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 Times of London report says that two senior members of her staff claimed they were bullied and another former employee was personally "humiliated" by the duchess. No action was taken at the time about the bullying claims, according to the report.

Buckingham Palace did not respond on Wednesday to a list of questions sent by NBC News.

Knauf still works for Harry's brother, Prince William, and was a key figure in Meghan's successful legal action against British tabloid The Mail on Sunday for printing a private letter to her father.

Harry spoke with late-night host James Corden last week about the couple's dealings with the British press when discussing why they decided to break from their royal duties.

"It was a difficult environment, as I think a lot of people saw," he said. "We all know what the British press can be like, and it was destroying my mental health."