Prince William and his wife Catherine have reacted with fury after a French magazine published topless photos of her, saying it raised the spectre of press harassment of William's mother Diana.
The young British royals, who are currently in Malaysia, were consulting lawyers over what they called a "grotesque" breach of privacy by the French version of Closer magazine, palace officials said.
The exclusive grainy pictures show Catherine, 30, wearing just the bottoms of bikini and having sunscreen rubbed onto her by William while on holiday in the south of France.
"Their royal highnesses have been hugely saddened to learn that a French publication and a photographer have invaded their privacy in such a grotesque and totally unjustifiable manner," St James's Palace said.
"The incident is reminiscent of the worst excesses of the press and paparazzi during the life of Diana, Princess of Wales, and all the more upsetting to the Duke and Duchess for being so."
The statement said officials acting on behalf of the couple "are consulting with lawyers to consider what options may be available to the Duke and Duchess".