The Duke and Duchess of Cambridge's lawyers are to appear in court in Paris on Monday to stop further publication of topless shots of the duchess.
The photographs have appeared in French magazine Closer and the Irish Daily Star. An Italian magazine has said it also plans to print the photographs.
Lawyers representing the couple will also seek damages.
It comes as the royal couple visit the Solomon Islands as part of a tour of south-east Asia and the South Pacific.
BBC correspondent Nicholas Witchell said the royal couple looked relaxed and happy as they arrived on the island as part of their nine-day tour as part of the Queen's Diamond Jubilee celebrations.
He added that they received a cheerful welcome as they were driven along streets lined with thousands of people.
Royal officials are said to be in close contact with London about the ongoing row, our correspondent says.
The co-owners of an Irish tabloid daily which also published the shots have condemned the decision to print.
The royal couple are to sue French magazine Closer, which is run by a different company from the British version, for invasion of privacy.
Closer magazine has defended its decision to publish the photographs, saying: "The photos we selected are by no means degrading.
"They show a young couple on vacation, beautiful, loving, modern in their normal life."
A spokesman for St James's Palace said official legal proceedings would begin on Monday when papers were served.