Six media representatives will go on trial Tuesday (2 May) over the publication of long-lens photographs of the Duchess of Cambridge sunbathing topless in France.

The photos of Kate and husband Prince William were published in the glossy French magazine Closer and the regional daily newspaper La Provence in September 2012, causing a furious reaction from the royal family.

The royal couple had been holidaying in southern France at a chateau owned by Viscount David Linley, the son of Princess Margaret, when the snaps were taken.

Buckingham Palace had called the photo spread a "grotesque" invasion of the royal couple's privacy, with Prince William and Kate taking legal action in France soon after their publication.

An investigation by French authorities also took place.

Laurence Pieau, the editor of Closer in France, Ernesto Mauri, chief executive of the Mondadori group which owns the magazine, and Cyril Moreau and Dominique Jacovides, two Paris-based agency photographers suspected of having taken the topless photos, are to appear on charges of invasion of privacy and complicity. La Provence's publishing director at the time, Marc Auburtin, and the photographer Valerie Suau also face related charges.

Closer has always refused to divulge the identity of the photographer, while La Provence denied Suau's involvement, AFP reported.

Prince William and Kate are not expected to attend the trail as it gets underway in the western Paris suburb of Nanterre.

At the time of their publication, Pieau defended the photos, saying they were "not in the least bit shocking". "I have to get exclusives. So I get exclusives. From my point of view, I did my job," she told the Observer.

But the pictures caused a scandal in Britain, where several national newspapers rejected offers to buy the photos.

The lawyer for Prince William and Kate, Aurelien Hamelle, launched legal proceedings shortly after they were published to ban the republication or resale of the photos.

He said the pictures were particularly distressing for the couple as it brought back memories of William's late mother Princess Diana's death in a car crash in Paris in 1997 while being pursued by paparazzi.

Hamelle described the Duchess of Cambridge as a "a young woman, not an object", adding that the couple had suffered a "grotesque breach of privacy" and felt "violated" during a "highly intimate moment during a scene of married life".

The French courts banned any further publication of the pictures, but the topless photos went on to appear in several other European publications, including in Italy, Sweden, Denmark and Ireland.