William and the former Kate Middleton on Monday initiated criminal proceedings under French privacy law as well as seeking an injunction to prevent further distribution of the pictures by France’s Closer magazine.
The injunction request was due to be considered at an emergency hearing scheduled for 1600 GMT on Monday.
No defendant was named in the criminal complaint but aides to the royal couple have said they want action taken against both Closer, which published the pictures on Friday, and the photographer who used a powerful telephoto lens to snap them poolside during a short break at a chateau in southern France earlier this month.
William was reported by the British media to have insisted on going after the photographer in a case which has evoked painful memories of paparazzi harassment of his late mother Diana.
The former Princess of Wales died in 1997 when the car she was travelling in crashed in a Paris tunnel while trying to escape chasing photographers.
The photographer who took the pictures which appeared in Closer on Friday, and have since been published in Ireland and Italy, has not been identified and Closer has refused to name him or her.
Legal experts say the magazine should be able to maintain that stance.
“The identity of the photographer raises the question of the secrecy of sources,” advocate Christophe Bigot told AFP.
“In principle, a judge cannot force Closer to disclose it as that would be a breach of legislation protecting journalistic sources.”
The law does provide for exceptions to be made but a judge would have to show “an overwhelming public interest” in it being bypassed, Bigot added.