On a website publicising Chi – owned by former Italian prime minister Silvio Berlusconi – Kate, who is about four months’ pregnant, is pictured on the magazine’s front cover in a blue bikini striding knee-high through the sea above the headline “the belly grows”.
A second image shows the Duke, wearing a pair of shorts, with his left arm around his wife as they walk along a beach.
A St James’s Palace spokesman said on Tuesday 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.”
William was left visibly outraged by the intrusion into his wife’s privacy while they stayed at a private estate in southern France last summer.
France’s Closer magazine was the first publication to print the images in September last year and the Duke and Duchess later succeeded in getting an injunction from a French court stopping further pictures appearing in the title.
At the time Chi’s editor Alfonso Signorini defended his decision to also publish the topless pictures, saying: “I am a director of a newspaper not a supermarket, I don’t sell artichokes and carrots, I sell photographic scoops.”