Lawyers acting for Prince William, second in line to the British throne, have threatened legal action if U.K. media repeat rumors published in an American magazine about him having an affair with an aristocratic friend.

“In addition to being false and highly damaging, the publication of false speculation in respect of our clients’ private life also constitutes a breach of his privacy pursuant to Article 8 of the European Convention to Human Rights,” a letter from top London law firm Harbottle and Lewis stated, according to the Daily Beast.

British outlets have published stories about Catherine, the Duchess of Cambridge, 37, the former Kate Middleton, having a falling out with their neighbor, Rose Hanbury, the Marchioness of Cholmondeley, a former model. Some have seen the reports as an allusion to a supposed affair between Hanbury and the prince, 36.

Hanbury, 33, is married David Rocksavage, 58, the 7th Marquess of Cholmondeley. They have twin boys, Alexander, Earl of Rocksavage, and Oliver, Lord Cholmondeley, and a daughter, Lady Iris.

The Duke and Duchess of Cambridge are greeted by the Marchioness of Cholmondeley (left) as they attend a gala dinner at Houghton Hall in King's Lynn. (Stephen Pond/PA Wire/Press Association Images)

The Cholmondeleys live in the 106-room Houghton Hall, near the Queen’s Sandringham estate. The two couples are said to have become close after the Cambridges moved to their country home, Anmer Hall, in 2014. The royal couple now lives in Kensington Palace.

Hanbury sat next to Prince William's younger brother Prince Harry at his first state banquet in 2017. Her grandmother was a friend of Queen Elizabeth II and a bridesmaid in her wedding to Prince Philip. Hanbury has been friends with the Duke and Duchess of Cambridge for over a decade and attended their wedding.“The two couples are thought to have regularly double-dated," the Tatler reported.

In Touch magazine became the first print outlet to details rumors of the alleged affair, said to have taken place while Kate was pregnant with their third child, Prince Louis of Cambridge, born last April.

After the duchess heard the rumors, according to In Touch, she “immediately confronted” William who “just laughed it off saying there was nothing to it.” But she allegedly ordered her husband to stop socializing with the marchioness.

In Touch said the rumors had “rocked the palace and their marriage” and has prompted comparisons to Prince Charles’ relationship with Camilla Parker Bowles while he was married to Princess Diana.

William and Kate sued a French magazine and was awarded $115,000 in damages after topless photos of the duchess were published.