Berlusconi's magazine publishes photos of pregnant 'bikini-clad' Duchess Kate
Palace sources have condemned the "violating" pictures, which show the couple walking along a beach while holidaying on the secluded Caribbean island of Mustique.
Gossip magazine Chi splashed pictures of the duchess and her growing baby bump across its front page, the 'Daily Mail' reported.
The pictures show the four months pregnant Kate wearing a bright blue halter-neck bikini with her slightly rounded stomach clearly visible.
Kate's arm is draped over her husband's shoulders while Prince William, who is wearing blue baggy shorts and sunglasses, has an arm protectively around his wife's back.
The headline on the magazine reads "Kate and William -honeymoon for three".
Royal sources said William felt "very bruised" about the fresh breach of privacy so soon after the same magazine splashed topless photographs of Kate across its front page beneath the headline "the queen is naked".
The source said William felt very strongly at the time that he had somehow "failed" to protect his wife.
The intimate photographs are thought to have been taken from a boat using a long lens camera.
The celebrity magazine, which is owned by former Italian prime minister Silvio Berlusconi, boasts: "The extraordinary images of the Duke and Duchess of Cambridge on their dream holiday in the Caribbean.
"The future mum, now four months pregnant, wore a tiny bikini which showed off her visible bump," it said.
The photographs are believed to have been offered to several other magazines around the world and could fetch up to 250,000 pounds.
"We are disappointed that photographs of the Duke and Duchess on a private holiday look likely to be published
overseas," a spokesman for St James's Palace has said.
"This is a clear breach of the couple's right to privacy," the spokesman said.
Meanwhile a palace source said: "It is violating".
The duke and duchess, who are expecting their first child in July, flew to a 19,000 pounds-a-week luxury villa on the island of Mustique last week.
This is not the first time the Italian magazine has created controversy. It had caused outrage when it published a photograph of Princess Diana as she lay dying.