The Duke and Duchess of Cambridge are to make a criminal complaint against the photographer who took topless pictures of her, St James's Palace has said.
Lawyers for the pair will make the complaint to the French prosecutor on Monday. The couple want the photographer or photographers responsible to be charged with a criminal offence for invading their privacy.
A palace spokeswoman said: "We can confirm that a criminal complaint is to be made to the French Prosecution Department tomorrow. The complaint concerns the taking of photographs of the Duke and Duchess of Cambridge whilst on holiday and the publication of those photographs in breach of their privacy."
Once the complaint is made, it is up to the prosecutors to decide whether to investigate and pursue it.
The news comes as royal lawyers prepare to attend the Tribunal de Grande Instance de Nanterre in Paris on Monday where damages and an injunction will be sought against France's Closer magazine, which was first to publish the notorious images.
The legal action aims to prevent further publication.
Closer is published by the Mondadori media group which also publishes Italian gossip magazine Chi which has promised a 26-page special edition featuring images of the royal couple on holiday but the palace said no decision has been taken on separate legal proceedings in Italy.
The case will begin in the afternoon and is expected to be held in public.
A palace spokesman said earlier on Sunday: "The court hearing is in France tomorrow when the official proceedings will start at a court in Paris as the papers have been served. It is the first airing and we will be seeking an injunction from them using the pictures and it will lead to a longer court case where damages will be sought."
French Closer, which is run by a different company from the British version, caused outrage earlier this week when it published the images of the couple enjoying private holiday moments at Chateau d'Autet, near Aix-en-Provence.