Public prosecutors have accused the 56-year-old of 102 counts of having or disseminating the illegal photos and videos. They believe he acquired the data and saved it on his mobile phone between May 2007 and January 2009.

Tauss maintains his innocence and has said he possessed the illegal materials as part of his research to fight child pornography. Investigators said they found “no objective evidence” of this claim, saying it had been “disproved.”

In September 2009 the Bundestag annulled Tauss’ parliamentary immunity, clearing the way for prosecutors to press charges.

After the scandal broke, Tauss’ lawyer criticised state prosecutors for staging a “public execution.”

In response to the investigation, Tauss left the centre-left Social Democratic Party, for which he has been an MP since 1994. He then became the first and only member of the Pirate Party in the Bundestag until the general election last September.

The Pirate Party in Germany sees itself as representing those in the information technology community, campaigning for privacy protection as well as the loosening of copyright laws.

He said he left the SPD in protest at its decision to support a bill giving the government the power to censor websites containing child porn.

Although Tauss is known for his experience in information technology matters, he said the decision to give the government powers to close such sites down is a mistake.