The move comes after a mounting week-long wave of off-and-online protests by mostly young Poles who fear the Anti-Counterfeiting Trade Agreement (ACTA) -- aimed at creating international standards for intellectual property protection -- could significantly curtail online freedom.

"If we find there really is justification to believe it (ACTA) poses a threat, we won't move to ratify it," centrist Prime Minister Donald Tusk told reporters.

Despite unprecedented outcry among Polish Internet users, Poland gave a nod to the agreement Thursday with an initial signature of endorsement, but ratification by parliament is necessary before it can take effect.

Poland's right-wing opposition Law and Justice party has raised the idea of holding a referendum on ACTA.

Poland's e-minister Michal Boni, a close Tusk aide charged with piloting the EU state's ACTA ratification, tendered his resignation Friday in the wake of the unprecedented wave of protest. Tusk, however, declined to accept it.

While Boni and Poland's culture minister had consulted on the document with record companies and commercial media, their failure to address groups representing Internet users has sparked public outrage.

Police in the southwestern city of Wroclaw told AFP Friday they had detained a 22-year-old student for questioning in connection with hack attacks which took down the prime minister's website for several days this week.

Weekend anti-ACTA cyber attacks by Anonymous and another hacker group called Polish Underground also took down the websites of Poland's president, parliament and foreign and culture ministers -- as well as national police headquarters, who were suffering yet another attack Friday.

Tens of thousands joined anti-ACTA street protests across Poland this week, organised largely via Facebook, with violence erupting at some events. Protesters have adopted as their own the now-iconic wryly smiling, mustachioed Guy Fawkes cartoon character masks of the global hacker group Anonymous.

Online protest pages on Facebook have attracted close to 400,000 supporters, while an anti-ACTA online petition had drawn about 147,000 signatures by Friday noon.

Social media activists were planning more anti-ACTA protests Friday, notably in the capital Warsaw.