The Duchess of Sussex has apologised in court for failing to remember authorising a senior aide to brief the authors of her and Harry’s unofficial biography.

Meghan submitted a statement to the court in which she said she could not remember emails between her and her then press secretary, Jason Knauf, about the unauthorised book.

It came as the court of appeal heard that the royal couple’s former communications secretary provided information to the Finding Freedom authors, Omid Scobie and Carolyn Durand. Knauf said in a witness statement that the book was “discussed on a routine basis”, which was “discussed directly with the duchess multiple times in person and over email”.

He also discussed meeting the authors to provide background information for the book and claimed Meghan provided him with several briefing points to share with them.

Knauf claims to have emailed Meghan’s husband, Prince Harry, about the meeting, to which the duke replied: “I totally agree that we have to be able to say we didn’t have anything to do with it. Equally, you giving the right context and background to them would help get some truths out there.”

Meghan apologised for misleading the court over whether Knauf provided information to the book’s authors in a witness statement released on Wednesday.

She said: “I accept that Mr Knauf did provide some information to the authors for the book and that he did so with my knowledge, for a meeting that he planned for with the authors in his capacity as communications secretary. The extent of the information he shared is unknown to me.

“When I approved the passage … I did not have the benefit of seeing these emails and I apologise to the court for the fact that I had not remembered these exchanges at the time. I had absolutely no wish or intention to mislead the defendant or the court.”

She added that she would have been “more than happy” to refer to the exchanges with Knauf if she had been aware of them at the time, adding they were “a far cry from the very detailed personal information that the defendant alleges that I wanted or permitted to put into the public domain”.

The Duchess successfully sued the publisher of the Mail on Sunday, Associated Newspapers Limited (ANL), over five articles that published parts of a “personal and private” letter sent to her father, Thomas Markle, in August 2018.

The high court ruled that the letter was unlawful and therefore avoided the need for a trial but ANL is challenging that ruling, arguing the case should go to a trial on Meghan’s claims including breach of privacy and copyright.

ANL’s lawyer, Andrew Caldecott, told judges that correspondence between Meghan and Knauf shows the duchess suspected her father might leak the letter to journalists, the Associated Press reported. Caldecott said the letter was “crafted with readership by the public in mind” and Meghan “was happy for the public to read if it Mr Markle were to leak it”.

He quoted from a witness statement in which Knauf said the duchess “asked me to review the text of the letter, saying, ‘Obviously, everything I have drafted is with the understanding that it could be leaked.’”

Knauf said Meghan asked whether she should address her father in the letter as “daddy”, adding that “in the unfortunate event that it leaked, it would pull at the heartstrings”.

In her own written evidence, the duchess said she had not believed that her father “would sell or leak the letter, primarily because it would not put him in a good light”.

“To be clear, I did not want any of it to be published, and wanted to ensure that the risk of it being manipulated or misleadingly edited was minimised, were it to be exploited,” she said.

The appeal hearing is scheduled to last until Thursday, with a ruling due at a later date.