Allegations reported by The Times said Meghan Markle had faced a complaint in October 2018 from Jason Knauf, who at the time was the Sussexes’ communications secretary.
The complaint alleged that she drove two personal assistants out of the household and undermined the confidence of a third member of staff, the paper said.
The Times said it had been approached by royal sources who claimed they wanted to give their account of the “turmoil” within the royal household.
Responding to the allegations, Meghan’s spokesperson said: “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.”
A Palace spokesperson declined to comment when contacted by The Independent.
The Times also reported that Meghan had attended a state dinner wearing earrings given to her as a wedding gift by Mohammed bin Salman, the Saudi crown prince.
The earrings were reportedly worn during a trip to Fiji which took place just weeks after the killing of journalist Jamal Khashoggi.
A US intelligence report released last week found the crown prince had approved the killing.
There is no suggestion that the duchess received the earrings in person, or that she has ever even met the crown prince.
The Independent contacted her representative for comment.
The report comes just days before Meghan and Harry’s interview with Oprah Winfrey is due to be aired.
The CBS two-hour special will be screened on Sunday in the US and is expected to be shown in the UK on 8 March.
The royal household will be braced for the show’s revelations as the couple discuss their life within the family and their exit from the working monarchy.
In a dramatic pre-released clip of the interview, Ms Winfrey asks Meghan if she was “silent or silenced”, with the duchess’s answer not revealed.
In response to a comment by the duchess, Ms Winfrey asks: ”Almost unsurvivable. Sounds like there was a breaking point?“
Harry is seen saying of his mother, Diana, Princess of Wales, while holding Meghan’s hand: “I’m just really relieved and happy to be sitting here, talking to you, with my wife by my side, because I can’t begin to imagine what it must have been like for her [Diana], going through this process by herself, all those years ago.”