Police raided two locations in Gothenburg on Tuesday and confiscated computers allegedly hosting so-called DC hubs, which connect file sharers through Direct Connect software.
A 28-year-old man has been questioned regarding the administration of the hubs.
A further three raids were conducted at two locations in Stockholm, and one in Kramfors in northern Sweden.
“A large number of computers and other equipment have been seized and it will take some time for the police to analyze them,” Fredrik Ingblad at the Stockholm City prosecutor’s office told The Local on Wednesday.
According to Ingblad, police suspect that the hubs have been used to allow users access to between 9,000 and 17,000 music files and the four are all suspected of copyright infringement.
“Two of the four have confessed, the other two have denied committing an offence but have confessed to having some involvement,” Ingblad said.
The police raids were conducted in response to reports from the International Federation of the Phonographic Industry (IFPI), which represents 95 percent of the music industry.
“There are far too many of these DC hubs in Sweden, we lead the world in this field I think,” Lars Gustafsson, chief executive of IFPI Sweden, told The Local on Wednesday.
“The police have had a shortage of resources for this type of crime but now it seems to be creeping up the list of priorities somewhat. That is something we welcome as it affects a lot of people within the music industry.”