The Duke and Duchess of Cambridge are said to be "saddened" after a French magazine published photographs of Kate topless.
The royal couple broke new ground by visiting a mosque for the first time during their tour of Malaysia, but all media attention was on the fact that another member of the royal family was at the centre of controversy over private images.
Closer magazine in France said the "exclusive" pictures showed Kate topless on the terrace of a guest house and were taken during a brief holiday she enjoyed with William in France last week.
The couple were staying in Provence at a chateau owned by Lord Linley, the Queen's nephew, ahead of their Diamond Jubilee tour of south-east Asia and the South Pacific on behalf of the Queen.
St James's Palace declined to comment, but speaking before the magazine hit the streets, royal officials said that if the photos were genuine and were published, it would be like "turning the clock back 15 years".
The magazine's French website showed an image of its new front cover with a heavily pixellated photograph of the Duchess in a bikini apparently about to remove her top. But the pictures were not pixellated in the magazine when it was published.
William and Kate were told about the pictures before they visited the Assyakirin Mosque and had also looked at the images on the website.
A source said: "They're saddened their privacy has been breached - if it has been breached... We will talk to our lawyers in London and counterparts in Paris to see what options are available." He went on to say: "We're not aware of anyone (in the UK) seeking to publish so the Press Complaints Commission is not coming into it."
The pictures are likely to reignite the controversy over privacy which raged around Prince Harry last month, when embarrassing images emerged of him frolicking naked in a Las Vegas hotel.
The Sun was the only British newspaper to defy a royal request issued via the Press Complaints Commission not to publish the photos of Harry in the nude with an unnamed woman.