Six photographers and journalists are set to appear in a French court on Tuesday (May 2) over topless pictures taken and published of Britain's Duchess of Cambridge in 2012.

The Duchess and her husband Prince William pressed at the time for criminal charges in France to try to prevent wider publication of the pictures, which were taken of them on a balcony of a private residence during their stay in the Luberon region.

Celebrity gossip magazine Closer was among the media who published the photos, with Buckingham Palace at the time calling the photo spread a "grotesque" invasion of the royal couple's privacy.

Tuesday's hearing will take place at a court in Nanterre, just outside Paris.