Poland's president approved new legislation to increase the government's surveillance powers, his office said on Thursday, despite fears that the new law undermines privacy.
The law may fuel a row between the European Union and Poland's conservative Law and Justice (PiS) party, which came to power after the October election.
The EU launched an unprecedented inquiry in January into whether Poland's new government has breached the EU's rule of law standards after passing new laws that critics say rein in the constitutional court and public media.
Poland's newest law expands the authorities' access to digital data and loosens the legal framework limiting surveillance by law enforcement. It comes into force on Saturday after its approval by President Andrzej Duda, a close ally of PiS.
Rights group Amnesty International described the law as "a major blow to human rights" and called a protest on Friday in front of the presidential office. Last month, thousands of people across the country protested against the law.
The Law and Justice (PiS) party, the first party to win an outright parliamentary majority since Poland's transition from communism in 1989, says surveillance must be expanded to counter the threat of terrorism.
The government said it had amended the bill to address an earlier ruling by the constitutional court, which said the bill was imprecise and lacked sufficient legal controls.
Poland's Ombudsman has said that some of the new bill may be still be unconstitutional, including parts that allow surveillance to be extended to up to 18 months, limits on court control, and a broader range of potential targets.
The Ombudsman's office said on Thursday that it will challenge the new law in the constitutional court.
A new PiS-sponsored law that came into force last year significantly increased the size of the majority the court needs to pass rulings.
That law, and another allowing the government to directly appoint heads of public media, sparked the EU investigation.
The Polish government has been defended by Hungary's eurosceptic Prime Minister Victor Orban and Syed Kamall, the leader of the conservative fraction in the European Parliament.