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 said tonight.
Lawyers for the pair will make complaint to the French prosecutor tomorrow.
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 tomorrow 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 today: "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.
The decision was roundly condemned but did not put off the Irish Daily Star carrying the images yesterday much to its owners' and the palace's fury.
The Duchess's distress was increased when Chi said it would publish more images of the pair on holiday.
Alfonso Signorini, the editor of Chi, which is owned by former Italian prime minister Silvio Berlusconi, said: "The fact that these are the future rulers of England makes the article more interesting and topical.
"This is a deserving topic because it shows in a completely natural way the daily life of a very famous, young and modern couple in love."
Today, French Closer were defending publication.
A statement on the magazine's website, said: "The photos we selected are by no means degrading.
"They show a young couple on vacation, beautiful, love, modern in their normal life."
The Irish Daily Star's decision to publish the photographs caused consternation among its joint owners, Northern and Shell and Independent News and Media (INM).
Northern and Shell chairman Richard Desmond said: "I am very angry at the decision to publish these photographs and am taking immediate steps to close down the joint venture.
"The decision to publish these pictures has no justification whatever and Northern and Shell condemns it in the strongest possible terms."
An Independent News and Media spokesman added: "The decision by the Irish Daily Star to republish pictures of the Duke and Duchess of Cambridge from the French magazine Closer was regrettable and in poor taste.
"Independent News and Media had no prior knowledge of the decision to publish."
But a boardroom row was on the cards as INM warned it would not be happy to see the tabloid shut down.
A company statement said: "Independent News and Media believes that a call to close the Irish Daily Star, which employs over 120 staff (directly and indirectly), is disproportionate to a poor editorial decision that occurred without reference to either shareholder.
"INM believes that the circumstances that led to the regrettable decision by the Irish Daily Star to re-publish pages from the French magazine 'Closer' warrant immediate investigation and steps are already under way in this regard."
The newspaper was operating as normal today with the newsroom preparing the first edition of the week and reporters and photographers on the beat.
The newspaper's editor, Michael O'Kane, appeared on television yesterday to defend publication but was unavailable for comment today.
Former prime minister Sir John Major backed the decision to take legal action over the pictures and likened the photographer's actions to those of a "Peeping Tom".
"I think it's absolutely right, so that people in the future know where the boundaries should be," he told BBC1's Andrew Marr Show.
"The boundaries have plainly been crossed. I don't think we need minced words about these photographs - the way they have been obtained is tasteless.
"It's the action of a Peeping Tom. In our country we prosecute Peeping Toms.
"That is what they have done, they have been peeping on long lenses from a long way away. they are very distasteful."
He said he "thoroughly applauds" the British press for refusing to use the photographs.