Pippa Middleton has launched a High Court action in what is thought to be an attempt to stop publication of hacked photos.
The Duchess of Cambridge’s sister is listed as the claimant in a case listed to be heard on Wednesday against a "person or persons unknown".
No other details are listed about the case.
It comes days after a man was arrested by police investigating claims Miss Middleton's iCloud account had been hacked.
A 35-year-old man has been released on bail.
Police said the man had been arrested at an address in Northamptonshire late on Saturday, on suspicion of a Computer Misuse Act offence.
Officers said he had been released on bail pending further inquiries.
Pictures of the Duchess of Cambridge and her children, Prince George and Princess Charlotte, are reportedly among 3,000 images taken from Miss Middleton.
Private photographs were said to have been offered to The Sun and Daily Mail newspapers, via encrypted messaging service WhatsApp.
