Pope Benedict XVI (search) on Monday endorsed efforts by Italy's Roman Catholic bishops to restrict assisted fertility treatments, stepping into an emotionally charged Italian referendum battle.

The German-born pope contended that next month's plebiscite on scrapping parts of a law that regulates assisted fertility treatments (search) posed threats to life and the family.

The pope spoke to the Italian bishops' conference, which has called on Italians to boycott the June 12-13 referendum.

He did not mention any details of the law but noted that the bishops were "committed to illuminating the choices of Catholics and all citizens" in the upcoming referendum. He emphasized the importance of defending the family and human life.

While it was his first foray into an Italian issue, the pope's support was not unexpected. Cardinal Camillo Ruini, the head of the Italian bishops' conference, is the pope's vicar for Rome.

For years, Italy had no laws on assisted fertility, giving the country something of a free-for-all reputation in the field.

The current law forbids sperm and egg donation, limits the number of embryos created with in vitro techniques to three and bans all embryo research (search).

The referendum would abrogate the law's provisions on embryo research, the three-embryo limit, the ban on egg or sperm donation from outside the couple and the attribution of rights to the unborn.

Opponents of the law complain it restricts scientific research and a woman's reproductive rights. Some also say it harms women, since it bars the freezing of embryos and thus forces women to be implanted with as many as three embryos.

The ANSA news agency reported that 85 percent of the physicians at Italy's largest gynecological hospital in Turin support changing the law and that more than 100 of the doctors issued a public appeal Monday for Italians to vote.

A communist politician, Franco Giordano, went on Radio Radicale and called the pope's remarks an "unwarranted interference in the affairs of the Italian state."

The Vatican faced similar accusations of interference in church-backed referendums in 1974 and 1981 that unsuccessfully sought to overturn laws permitting divorce and abortion.

The bishops are pressing Italians not to vote in the hope that a low turnout will doom the proposed changes to the law. At least 50 percent plus one of eligible voters must cast ballots to make a referendum valid.

Benedict stressed that the family was "fundamental" to Italian society. But he said that even in this overwhelmingly Roman Catholic country, the family has not been immune to secular trends.

"Even in Italy the family is exposed to the current cultural climate, therefore to risks and threats that we all know," he said.

He cited the "tendency of the culture to challenge the unique character and the mission of the family based on a man and a woman" — a reference to acceptance in some countries to same-sex marriage.