The chief prosecutor in the case, Ruediger Rehring, has said the results of the investigation have been sent to Tauss's lawyers. "We continue to believe that Mr Tauss has committed a punishable offence in holding child pornography in the form of computer files and pictures," he told the German news agency dpa.

The material - allegedly mobile-phone pictures and DVDs - was found in Tauss's office in March. He has always insisted that he was investigating the processes by which child pornography is obtained as part of his duties as media policy spokesman of the Social Democrat parliamentary group.

According to Germany's Bild newspaper, the prosecutor's report concludes that Tauss had not been officially tasked with the investigation, so that his defense would not stand.

"Social execution"

Tauss's lawyer, Jan Moenikes, accused the prosecutor of having made up his mind about his client's guilt from the start. He accused him of "social execution."

Following the discovery, Tauss resigned from his position, and later left the SPD altogether to join the Pirate Party, a new grouping which will be standing in the forthcoming national election to campaign for greater freedom on the internet.

Last week, a Pirate Party spokesman, Fabio Reinhardt, told Deutsche Welle that Tauss had been trying to show that new laws intended to stop child pornography from circulating on the internet were useless.

"Joerg Tauss has never downloaded child pornography," he said. "I have never heard of anybody who has downloaded child pornography. What he wanted to do is find out himself how child porn is spread, and what he found is that child pornography is mostly spread via telephone hotlines and normal mail."

He admitted that Tauss should have left such investigations to the police, but he said he was convinced that Tauss was not a user of child pornography.

Bundestag vote needed

Before charges can be brought, a draft version of the charges will be presented to the parliamentary committee on immunity which will make its recommendation. Rehring said the Bundestag could vote on the matter before the next election, during special sessions in late August or early September which will be called to pass new rules to conform with a recent finding by the Constitutional Court on the EU Lisbon Treaty.

mll/dpa/AP/AFP
Editor: Neil King