A group calling itself 'Den nya generationen' (The new generation) left a message saying that the site was hacked in support of the defendants in the case. It was also a "declaration of war on the anti-piracy industry and the players behind it, and we call on the general public to boycott and lynch those responsible. IFPI is just the start. To be continued."
But Pirate Bay spokesman Peter Sunde, one of the four men on trial for being an accessory to copyright infringement, was quick to distance the file sharing site from the attack on IFPI's homepage.
"It was a really stupid thing to do. It just gives us a bad image, especially when we're in the process of winning this case," he told news agency TT.
Sunde, who is also blogging about the case using his online alias "brokep", posted a message on Thursday with the title, "We're winning, stop hacking plz", urging the perpetrators to keep a lid on their emotions.
Lars Gustafsson, managing director of IFPI, said his organization was accustomed to online attacks any time it took steps to curtail illegal file sharing.
"The odd thing about this internet mob that promotes freedom of speech and freedom of information is that it only seems to apply to them," he told TT.