Two men were arrested on Monday morning on suspicion of copyright infringement and money laundering in connection with the BitTorrent site T411, Swedish daily Dagens Nyheter reported.
Like other torrent sites, T411 offered users the chance to download music, games, and films, without hosting the files itself. While relatively unknown in Sweden, the site was one of France's most visited, and as of 2013, boasted over 5 million members.
T411 went offline on Sunday evening, prompting speculation in the tech world over whether this was due to maintenance or a police swoop.
On Tuesday, Swedish police confirmed that two men suspected of running the site had been arrested on suspicion of copyright infringement and money laundering. The police raid took place in Huddinge, a suburb south of Stockholm.
"It's an ongoing operation which I am leading in cooperation with the French authorities," district prosecutor Henrik Rasmusson told Dagens Nyheter. "There is a parallel effort in France. Our investigation is about questioning the persons and sending evidence to the French authorities.”
Rasmusson added that the suspects were not Swedish citizens, but were in the country legally.
The file-sharing site was created in 2006 as QuebecTorrent, and went through several name and domain changes before its reincarnation as T411 in 2011.
It had been subject to complaints from Sacem, the French society for musicians and composers and France’s anti-piracy organization (ALPA). A 2015 US government report by the Recording Industry Association of America (RIAA) listed T411 as one of 57 "notorious pirate sites".
Both France and Sweden have recently cracked down on torrent sites. Last year, French police shut down several of the country's largest such sites, including Zero-Telechargement and What.cd.
And in Sweden, a long-running case over the legitimacy of file-sharing site Pirate Bay came to a conclusion earlier this year when an appeals court ruled a broadband provide must stop its customers accessing the site. Founded in Sweden in 2003, The Pirate Bay grew into a leading force in file sharing by allowing users to access torrents for music, films, games and other copyrighted material free of charge.