Britain's royal family said on Sunday it would seek legal damages from French magazine Closer as it tries to prevent the spread of topless photos of Prince William's wife Catherine.
The couple's legal team will also seek an injunction at a court hearing in the Paris suburb of Nanterre on Monday to prevent further publication of the pictures.
"We will be seeking an injunction from them (Closer) using the pictures and it will lead to a longer court case where damages will be sought," said a spokesman for St James's Palace.
In a fresh blow to the royals the images appeared again in Saturday's Irish Daily Star.
"There can be no motivation for this action other than greed," said a spokeswoman for Catherine and her husband, the second-in-line to the British throne.
Italian gossip magazine Chi, meanwhile, is planning to devote 26 pages to the grainy paparazzi photographs in a special issue on Monday -- a move the palace said would heap "unjustifiable upset" on the former Kate Middleton.
Both Closer and Chi are published by the Mondadori Group, part of the media empire of former Italian prime minister Silvio Berlusconi.
The company backed both magazines' decisions to print the photos, which were taken with a long lens while William and Catherine, both 30, were holidaying at a private chateau in the south of France.
"The editors of both titles decided to publish the photos because their content is a clear expression of the news, they depict a true event, and they do not undermine the people photographed," Mondadori said in a statement.
Chi magazine's editor Alfonso Signorini said the pictures were "a scoop" he could not afford to miss.
"If I wasn't capable of recognising the true value of a scoop I would do better to go and sell artichokes at the market," he told the ANSA news agency.
He said did not ask Berlusconi's permission to print the images.
A palace spokeswoman declined to comment on whether the royal family was launching legal action against either Chi or the Irish Daily Star.
"All proportionate responses will be kept under review," she said.
Former British prime minister John Major said on Sunday it was "absolutely right" that the couple had initiated legal proceedings. Speaking on the BBC, Major branded the offending publications "peeping Toms".
Unlike Mondadori, the two media groups that jointly own the Irish Daily Star condemned its decision to run the pictures.
Britain's Northern and Shell group said it was taking "immediate steps" to shut down the joint venture with Dublin-based publisher Independent News and Media which runs the Irish Daily Star.
"The decision to publish these pictures has no justification whatever and Northern and Shell condemns it in the strongest possible terms," said the company's chairman Richard Desmond.
Independent News and Media said it had no prior knowledge of the decision, which it described as "regrettable and in poor taste".
The Irish Daily Star's editor Mike O'Kane admitted that he was running the pictures to sell more papers, and said he had treated Catherine as he would any other celebrity.
"The duchess would be no different to any other celeb pics we would get in, for example Rihanna or Lady Gaga," he told the BBC on Saturday.
The photos would not appear in the British or Northern Irish editions of the Daily Star, he added.
The prince is said to be furious over the images, which drew comparisons with press harassment of his mother Diana who died in a Paris car crash in 1997 while pursued by paparazzi.
The prince is believed to blame the press photographers for his mother's death.
In a strongly worded statement, palace officials described the topless pictures as a "grotesque" breach of privacy.
"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," they said.
The palace has said the couple "remain focused" on their nine-day southeast Asian and Pacific tour marking Queen Elizabeth's 60 years on the throne, which on Sunday took them to the lush Solomon Islands.
Their Pacific islands leg includes an ocean-themed motorcade and Jubilee Thanksgiving service in the capital's cathedral before a traditional island feast in the Government House gardens.
The couple are also to make a short stop in Tuvalu, one of the world's smallest independent nations, lying about halfway between Australia and Hawaii.