(WARSAW, Poland) -- Despite efforts by conservatives and religious leaders, Polish President Aleksander Kwasniewski refused to sign a sweeping anti-porn bill into law Monday because of fears it would be unenforceable and damaging to the state's credibility, aides said.

The controversial bill, narrowly approved by parliament March 3, would have banned the import and distribution of both soft- and hard-core pornography in what would have been among Europe's toughest anti-porn laws.

The measure reflected concern in Poland about the growth of a thriving sex industry since the collapse of communist rule in 1989 resulted in a more liberal atmosphere and opened the country to Western social influences.

Debate over the anti-porn bill has pitted Kwasniewski, an ex-communist who is one of Poland's most popular politicians, against conservatives in the Solidarity-led government and the influential Roman Catholic church.

Kwasniewski's aide, Jolanta Szymanek-Deresz, said Monday night the president decided to veto it because he believed the bill went so far that it would have been ignored, damaging the prestige of the state and of the law.

Opponents of the bill, including Kwasniewski's allies in the leftist opposition, contend it went overboard in limiting freedom of expression and would have spawned a thriving black market in pornographic videos, films and literature.

It also was opposed by Solidarity's junior coalition partner, the Freedom Union, in part because it left to the courts the tricky decision of what constitutes pornography.

The ban had called for fines and prison terms of up to two years on violators. In cases involving child pornography, five-year prison terms were proposed.

Current law permits the distribution of so-called soft porn, but distribution of hard-core pornography that includes violence, children or animals is punishable by up to five years in prison.

The proposed ban was widely seen as another effort by the Catholic Church to influence Polish politics. The church stirred controversy in the early 1990s by pushing through legislation introducing religious classes in public schools and a strict abortion ban.

A recent public opinion survey showed that 48 percent of Poles disapproved of the ban, while 42 percent supported it. The poll was conducted March 10-13 by the Demoskop agency, which calculated the survey's margin or error at plus or minus 3 percent.