Gottfrid Warg, the co-founder of notorious file-sharing site Pirate Bay, has been sentenced to three-and-a-half years in prison for hacking offences.

Warg and his co-defendant were charged with illegally accessing computers owned by technology firm CSC and downloading police and social security files.

Read more: Illegal downloaders to receive email warnings, as Pirate Bay traffic doubles

According to the BBC, prosecutors described the trial as the "largest hacking case to date."

Warg's accomplice received a six-month prison sentence, but was free to leave court having already spent 17 months in pre-trial detention. Representatives for Mr Warg have confirmed that the Pirate Bay founder will be lodging an appeal.

The alleged hack took place back in February 2012, but lawyers for the defence have claimed that, although the attacks were carried out using Warg's computer, he was not responsible. Instead, they maintain that another unnamed hacker was responsible.

The judge and jury, however, have dismissed this line of argument as "unlikely."

It is also not the first time that Warg has got into difficulties with the law. In September 2013, he was deported from Cambodia to his native Sweden to face sentencing for copyright theft relating to his involvement with the Pirate Bay.

In a separate case that year, Warg was also sentenced to two years imprisonment for hacking into a bank's computer, before seeing the sentence reduced to one year.

Read more: Kim Dotcom's extradition hearing delayed until next year

It wasn't until late November 2013 that he was deported to Denmark to face charges relating to the CSC hacking case.