The Duchess of Sussex sanctioned a close friend to try to influence a story about her in the media, court documents claim.

Meghan “caused or permitted” confidant Jessica Mulroney to contact her former commercial adviser, who had given an interview to the Mail on Sunday, in a bid to ensure “a more favourable article was published”, it is alleged.

The claim is made in a legal document submitted to the High Court earlier this year by the publisher of the Mail on Sunday and MailOnline. The organisation is facing legal action launched by Meghan over an article that featured parts of her handwritten letter to her estranged father Thomas Markle.

Ms Mulroney, a Canadian stylist and TV star, wrote to Gina Nelthorpe-Cowne “putting pressure on her to withdraw or change statements” around April 2018, claims the defence document for Associated Newspapers.

It claims the Sunday newspaper’s features editor complained about the intervention of Meghan’s friend, with Harry’s then-communications secretary Jason Knauf allegedly responding by saying he would ensure “this does not happen again”.

Associated Newspapers’ legal team said in the document it would seek from Meghan communications relating to what it alleges are Ms Mulroney’s intervention and any other occasions the duchess “caused or permitted her friends to provide information about her to the media or to seek to influence what is published about her.”

Ms Mulroney supported Meghan in the difficult days leading up to her wedding amid the turmoil caused by the absence of her father.

Her children – twin boys Brian and John and daughter Ivy – were pageboys and bridesmaid at the royal nuptials staged at St George’s Chapel in Windsor Castle in May 2018.

She is married to Ben Mulroney, son of former Canadian prime minister Brian Mulroney.

The duchess is bringing a privacy claim against Associated Newspapers over the publication of the “private” letter in February last year in The Mail On Sunday and MailOnline.

Meghan is seeking damages for alleged misuse of private information, copyright infringement and breach of the Data Protection Act.

Associated Newspapers wholly denies the allegations – particularly the claim that the letter was edited in any way that changed its meaning – and says it will hotly contest the case.