Photos of Prince William and his pregnant wife Kate Middleton on a private Caribbean holiday have sparked fresh anguish for the Royal family.

The images show Kate, who is three months pregnant, walking on a beach with Prince William on the island of Mustique. The couple enjoyed a vacation there at the end of January with the Duchess’ family.

The images have been published by Chi magazine, which is owned by former Italian prime minister Silvio Berlusconi. The same publication produced a 26-page spread after snaps of Kate posing topless while on holiday in France were released.

On Wednesday, Chi's editor in chief, Alfonso Signorini, defended his decision to run the photos.

"We cannot talk about a violation of privacy when we publish pictures of public people in a public place. The photographs of Kate and William were bought from an international photo agency," Signorini told Us in a statement. "You can't compare this with the media persecution of Lady Diana. I cannot stress enough that the photos were taken in a public place, not private property."

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It is understood the Royals stayed in one of the 74 private villas on the 1,400-acre private island. Queen Elizabeth and  Prince Philip have also visited the Caribbean location.

According to the MailOnline publishers in the United States, France and Germany have also bought the images for more than £100,000 in total.

A St James's Palace spokesman said last night: "We are disappointed that photographs of the duke and duchess on a private holiday look likely to be published overseas.

"This is a clear breach of the couple's right to privacy."

The photos were reportedly snapped by a photographer on a boat using a long lens camera.

Prince William is currently on a six-week tour of duty with his search-and-rescue helicopter team in the Falkland Islands.