Though Kate Middleton and Prince William were hoping for an escape on their sunny vacation on the Caribbean isle of Mustique, an Italian magazine managed to snap pictures of the pregnant Duchess of Cambridge and leaked them out for the world to see.

The magazine - which is owned by the family of Silvio Berlusconi, the former Italian premier who was criticized when he informally greeted the Queen on a previous occasion - published the notorious photographs of Kate topless last year and also published pictures of Princess Diana's final moments after the Paris car crash that took her life. The latest pictures include a double page spread showing William - wearing blue stripey board shorts - strolling on the beach with bikini-clad Kate's arm around his shoulders.

A royal spokeswoman said the publication was "a clear breach of the couple's right to privacy".

"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," added the spokeswoman for St James's Palace.

The paparazzo shots could have been taken from as far away as an offshore boat and have sparked a bidding war in the thousands of dollars, according to Hollyscoop.

"It's been a real sour note for the end of their trip," a source tells Us Weekly. "For Catherine, it was the first time she had shown her baby bump, and so for it to be exposed so quickly has shaken her up a little. They thought with the privacy laws on the island they would be able to spend a moment outside of the house without this happening."

The duchess has been keeping a mostly low profile since the pregnancy was announced last December. She is set to make her second official appearance since the pregnancy at a London charity on Feb. 19.

No word on whether the royals will take legal action against the publication.