Public prosecutors in Kassel, western Germany, said on Friday that police had seized thousands of telephones, computers, hard drives,USB sticks, DVDs and CDs in raids across the country.

“This is not the biggest case in German history but it has an extraordinary dimension,” the public prosecutor’s office in Kassel said in a statement. It added that it was the first time police in Germany had found mobile phones being used to distribute pornographic pictures via MMS multimedia messaging technology on such a large scale.

The search, codenamed “Operation Susi,” was launched after investigations against a 33-year-old man near Kassel found his mobile phone contained the numbers of more than 400 men and some women to whom he had sent as well as received pornographic images from.

Most of the suspects, whose ages range between 20 and 83, are said to be from the state of North-Rhine Westphalia while 76 are from Bavaria. The more than 400 raids carried out this week across Germany have still not led to any arrests.

“We still don’t know how the suspects communicated with each other and whether there is a mastermind behind the network,” said Klaus Quanz, head of the police operation near Kassel in the state of Hesse.

Prosecutors have said the investigations are proving to be extremely difficult because the courts needed to examine each search warrant individually.

Public Prosecutor Hans-Manfred Jung said most of the suspects were being investigated for the possession of child pornography, a charge which carries a prison sentence of up to two years.

“We’re now looking for indications of actual abuse. Legally, that would then put the whole affair in a totally different league,” he said.