The judge who presided over the recent Pirate Bay trial has denied he had a "conflict of interest", after a Swedish radio station revealed he is a member of the country's main copyright association.

Sveriges Radio, described as Sweden's answer to the BBC, said that judge Norström is not only a member of the Swedish Copyright Association but also sits on the board of the Swedish Association for the Protection of Industrial Property, an organisation that lobbies for tougher copyright laws. The four co-founders of Pirate Bay were found guilty last week of charges relating to copyright infringement.

Judge Norström today denied his involvement with the two pro-copyright organisations constituted a "conflict of interest" in his ability to preside over the most high-profile trial involving illegal filesharing in European history. The defendants, Fredrik Neij, Gottfrid Svartholm, Peter Sunde and and Carl Lundström, were found guilty on 33 specific charges of making files accessible for illegal sharing. They have been ordered to pay a fine of €2.7m (£2.4) and have been sentenced to one year in prison. The verdict was decided by both the judge and jury.

The trial became the focus of media attention when the co-founders, who Twittered their version of events throughout the trial, were given jail terms for their role in Pirate Bay. The verdict is being treated as a major victory by the entertainment industry, while those opposed to the verdict point out that Pirate Bay technically acts as torrent site and does not actually host files itself.

On hearing the news today, defence lawyers said they would be calling for a retrial. "I will point that out in my appeal, then the court of appeal will decide if the district court decision should be set aside and the case revisited," Peter Althin, Peter Sunde's lawyer, said today.