"The trial may have to be redone. But in such case the lawyers have to request this immediately," one of Sweden's most high-profile defence lawyers, Leif Silbersky, told public broadcaster Swedish Radio.

His comments came after the radio station revealed one of the judges in the case, Tomas Norstroem, belongs to several copyright protection associations where film and record industry officials are also members.

On April 17, Stockholm's district court sentenced Fredrik Neij, Gottfrid Svartholm, Peter Sunde and Carl Lundstroem each to a year in jail and ordered them to pay damages of 30 million kronor (2.72 million euros, 3.56 million dollars) to the movie and recording industry.

The four vowed to appeal the verdict.

Sunde's defence lawyer, Peter Althin, said Thursday he would demand a retrial.

"In my appeal I'm going to argue that (the judge was biased). The court of appeal can then decide whether the district court's verdict should be thrown out and the case retried," Althin said.

Norstroem is a member of the Swedish Copyright Association, as are Monique Wadsted, who represented the film and recording industry in the trial, and the head of the Swedish Anti-Piracy Agency, Henrik Ponten.

The judge also sits on the board of the Swedish Association for the Protection of Industrial Property.

Yet Norstroem insisted that he was not biased.

"I do not consider myself biased because of these affiliations," he said.

Eric Bylander, a lecturer in litigation law at Gothenburg's business school, said the judge's opinion mattered little.

"It can look bad, regardless of what the judge thinks. In a high-profile case like this, it surprises me that they weren't more cautious," he said.

A lay judge was removed from the case before the trial because of his own possible conflict of interest as a member of a composers' association.

Founded in 2003, The Pirate Bay makes it possible to skirt copyright fees and share music, film and computer game files using bit torrent technology, or peer-to-peer links offered on the site.

None of the material can be found on The Pirate Bay server itself.

The Pirate Bay claims to have some 22 million users worldwide.

(c) 2009 AFP