Lawyers for a British newspaper publisher are arguing that Meghan Markle made personal information public when she allegedly cooperated with the authors of a book about her and Prince Harry as part of the couple's ongoing invasion of privacy lawsuit.

The Duchess of Sussex is suing the publisher of the Mail on Sunday and the MailOnline website over five articles that published portions of a handwritten letter she wrote to her estranged father, Thomas Markle, after her marriage to Harry in 2018.

Meghan, 39, is seeking damages from publisher Associated Newspapers Ltd. for alleged misuse of private information, copyright infringement and data protection breaches.

Associated Newspapers, however, is contesting the claim. At a hearing Monday at the High Court in London, the publisher sought to amend its defense in light of a book about the couple that was published last month titled "Finding Freedom."

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It said the book, “contains a great deal of detailed information about (Meghan’s) personal life, including a number of passages referring to her relationship and communications with her father, and a section referring to the letter which is at the heart of this case.”

Antony White, the lawyer for Associated Newspapers, said in written submissions that the book appeared to have been written with Meghan and Harry’s “extensive cooperation.”

Justin Rushbrooke QC, who is representing Meghan, the Duchess of Sussex, arrives at the High Court in London, Monday, Sept. 21, 2020. The next stage in the Duchess of Sussex's legal action against a British newspaper over its publication of a "private and confidential" letter to her estranged father is due to be heard at the High Court.  (AP Photo/Kirsty Wigglesworth)

Meghan’s lawyers denied that she cooperated with the authors of the book, Carolyn Durand and Omid Scobie

“The claimant and her husband did not collaborate with the authors on the book, nor were they interviewed for it, nor did they provide photographs to the authors for the book,” Meghan’s lawyer Justin Sherbrooke said in a written submission.

Monday’s court session was the latest preliminary hearing in the high-cost, high-profile case. A full trial is scheduled to begin in January.

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Following an earlier hearing in May, a judge dismissed parts of Meghan’s claim, including allegations that Associated Newspapers acted “dishonestly” by leaving out certain parts of her letter to her father.

The judge also struck out allegations that the publisher deliberately stirred up issues between Meghan and her father and that it had an agenda in publishing intrusive articles about her.

Last month a judge ruled that the duchess can keep secret the names of five close friends who defended her anonymously in an American magazine against alleged U.K. media bullying.

Britain's Harry and Meghan, the Duke and Duchess of Sussex, arrive to attend the annual Commonwealth Day service at Westminster Abbey in London. Prince Harry has repaid 2.4 million pounds ($3.2 million) in British taxpayers’ money that was used to renovate the home intended for him and his wife, Meghan, before they gave up royal duties. A spokesman on Monday, Sept. 7, 2020, said Harry has made a contribution to the Sovereign Grant, the public money that goes to the royal family. (AP Photo/Kirsty Wigglesworth, file)

High Court Judge Mark Warby agreed, “for the time being at least,” to grant Meghan’s request to protect the anonymity of friends who defended her in the pages of a U.S. magazine in order to spare them a “frenzy of publicity” before the case comes to a full trial.

Markle, star of TV legal drama “Suits,” married Harry, grandson of Queen Elizabeth II, in a lavish ceremony at Windsor Castle in May 2018. Their son, Archie, was born the following year.

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Early this year the couple announced they were quitting royal duties and moving to North America, citing what they said was unbearable intrusion and racist attitudes from the British media. They recently bought a house in Santa Barbara, Calif.

The Associated Press contributed to this report.