The Anti-Counterfeiting Trade Agreement (ACTA) aims to create international standards for intellectual property protection, but some groups oppose it as limiting Internet freedoms. Poland has committed to signing ACTA on Thursday.

Shouting "Stop ACTA", about 2,000 mostly young Poles rallied outside the European Commission office in central Warsaw after what had been touted as a "silent" protest by organisers attracted over 40,000 "like" tags on a dedicated Facebook page.

"I certainly won't be able to download a lot of the music which I listen to now, to watch all my favourite foreign TV shows which I really enjoy and which we don't have on Polish TV," Patrycja Tchorek, a 19-year-old Warsaw resident who turned out to rally against the accord, told AFP.

Fotogaleria: Pikieta przeciwników ACTA w Warszawie

"Trying to impose limits on the Internet just doesn't make any sense," said 18-year-old Izabella, who declined to provide her last name.

Dozens of protesters wore the now-iconic smiling, mustachioed cartoon character masks of the global hacker group Anonymous.

Popular Polish websites including the satirical joemonster.org and demotywatory.pl also donned black shrouds and "Stop ACTA" banners.

The fresh wave of protest comes after weekend anti-ACTA cyber attacks by Anonymous and another group called Polish Underground took down the official websites of Poland's president, prime minister, parliament and foreign and culture ministers.

AFP