Meghan Markle, the Duchess of Sussex, has won a three-year High Court battle over the publishing of parts of a private letter to her father, Thomas Markle, 77. 

The Mail on Sunday has acknowledged Markle, 40, has won her copyright claim against the newspaper's publishers for printing extracts of the letter and has agreed to pay "financial remedies", reportedly to the tune of $NZ3.1 million. 

The acknowledgement on its front page is part of a series of demands successfully made by Markle in winning her case. 

The mother of two and wife of Prince Harry sued Associated Newspapers Limited (ANL), also the publisher of Mail Online, in August 2018 over five articles that reproduced parts of a "personal and private" note to her estranged dad, reports The Sun. 

The Mail on Sunday has printed a front-page apology to Meghan Markle, Duchess of Sussex. Photo / Mail on Sunday 

At the bottom of the Mail on Sunday's Boxing Day front page, it reads: "The Duchess of Sussex wins her legal case for copyright infringement against Associated Newspapers for articles published in The Mail on Sunday and posted on Mail Online – SEE PAGE 3." 

According to The Sun, page three presents the heading: "The Duchess of Sussex" and goes on to read: "Following a hearing on 19-20 January, 2021, and a further hearing on 5 May, 2021, the Court has given judgment for the Duchess of Sussex on her claim for copyright infringement. 

"The Court found that Associated Newspapers infringed her copyright by publishing extracts of her handwritten letter to her father in The Mail on Sunday and on Mail Online. 

"Financial remedies have been agreed." 

It is alleged the statement had been held while ANL sought permission to appeal. And at a November hearing it was argued the case should go to trial over Markle's claims against the publisher – including breach of privacy and copyright. 

Lawyers for ANL argued new evidence from former communications secretary to the Duke and Duchess of Sussex, Jason Knauf, points to Markle penning the letter knowing it could have been leaked. 

However, the challenge was dismissed by Court of Appeal judges earlier this month, reports The Sun. 

It was agreed the Duchess had a "reasonable expectation" of privacy when it came to the contents of her letter, which was deemed "not matters of legitimate public interest". 

While the Duchess won her case earlier this year, it is alleged that during the trial Markle had to apologise to the court. It is claimed she withheld details of emails that reveal attempts to influence a biography about her and Harry. 

In emails released by the Court of Appeal, it appears Markle and her husband "heavily briefed their press spokesman Jason Knauf before he met writers Omid Scobie and Carolyn Durand two years ago", reports The Sun. 

It is alleged the Duchess told the court she "forgot" about the briefings. 

Demands by Markle, whose royal brand with her husband is worth an estimated £250 million ($NZ493.25 million), included payment in legal fees and that copies of her letter be handed over by the publication and any electronic versions or notes made about it be destroyed. She also requested that the MailOnline run a piece on its homepage for a period of six months. 

The Sun reports that according to Markle's legal team, costs were estimated to be almost $NZ3.1 million and it was demanded that half be paid within 14 days. However, Lord Justice Warby ordered The Mail on Sunday to pay $NZ 1.2 million, with the potential for more to be paid later.