French police said they had arrested 90 people across the country on Tuesday in an operation targeting a network trading pedophile pictures on the Internet.

During an investigation that lasted several years, a police unit specializing in online crime identified people linked to a pedophile image-swapping server that was uncovered in 2005 and had been operated from an area north of Paris.

The person running that server was arrested four years ago but police traced dozens of its users and four people who had set up their own servers providing illegal pictures and videos.

In a swoop that stretched from Brittany to southeastern France, police seized several computers.

We discovered on the computers seized belonging to one person ... more than 30,000 images of children. That's the images. There were also around 1,000 videos, said James Juan, the public prosecutor of Beauvais, a town north of Paris, announcing the arrests alongside the police involved.

The 90 men arrested were held in police custody and face up to 10 years in prison.

(Reporting by Thierry Leveque; writing by Francois Murphy)