“The court of appeal has decided today to uphold the Södertörn district court’s decision to order an Internet service provider to give out the names and addresses of the holders of certain IP-addresses,” it said in a statement.

The court said its ruling against TeliaSonera was based on Sweden’s controversial Ipred law, which came into effect on April 1st last year and gives copyright holders the right to require service providers to reveal details of users who share files, paving the way for legal action.

If TeliaSonera does not give out its clients’ identities, it will have to pay a fee of 750,000 kronor ($96,523), the TT news agency reported.

The company was also ordered to pay the court fees.

On February 11th, TeliaSonera logged an appeal against the lower court decision forcing it to provide the names and addresses of those behind swetorrents.org website to Svensk Filmindustri, a Swedish film production and distribution company, among others.

The companies had argued Swetorrents violated copyright laws by making copyrighted material available through its homepage, and used the Ipred law to

force TeliaSonera to reveal the site operator’s identities.

Until the law was introduced, Sweden – home to one of the world’s most popular file sharing sites, The Pirate Bay – had widely been considered a haven for illegal file sharing.

While Swedish Internet use significantly dropped in the days after the introduction of the law – attributed to a decline in illegal downloading – the fall was only temporary, according to internet exchange point operator Netnod.

According to a Sifo survey published by broadcaster Viasat on April 1st the number of illegal file sharers is in fact increasing, with 16 percent of Swedes responding that they engaged in the practice.

While Netnod figures for April 2010 show that the short dip was part of a longer term steady upward trend, Ipred has been lauded by the music, film and video games industries.

The TeliaSonera case however represents only the second attempt by a copyright holders’ organization to utilize the new anti-file sharing law.

In June, the district court in Solna, north of Stockholm, ordered broadband provider Ephone to hand over information to five book publishers about a server from which audio books were made available for download on the internet.

Ephone has since appealed the ruling.

The new file sharing law is based on the European Union’s Intellectual Property Rights Enforcement Directive (IPRED).