Vatican City - Pope Benedict, taking his first plunge into Italian politics, on Monday backed a controversial campaign by bishops who have urged voters to boycott an emotionally charged referendum on assisted fertility.
The German Pope, addressing Italian bishops at the Vatican, praised them for trying to "enlighten the choices of Catholics".
Some promoters of the referendum, which aims to repeal a highly restrictive assisted fertility law, accused the Pope of meddling in politics and urged Italy's president to intervene.
The referendum has raised the political temperature in Italy for the past few months, pushing the country into the most tense debate over a moral issue since divorce and abortion were legalised the 1970s.
"Yes" votes would lift a ban on embryo research and remove limits on the number of eggs that can be fertilised during each attempt at insemination.
"Yes" votes would also lift a ban on egg and sperm donors and remove language giving fertilised eggs full legal rights.
The Pope said the Church, which has urged Catholics not to vote at all, was taking its stand to defend human life and not because it wanted to back certain political parties.
Benedict, who was elected last month, said he was close to the bishops "in word and prayer" and said their stand on the vote made them "truly good pastors".
While he did not use the word boycott, his praise was tantamount to the same thing since they have urged Catholics not to vote. A quorum of under 50 percent would make the referendum invalid and keep the law as it stands.
Catholic groups have passed out leaflets at Sunday Masses saying: "Life cannot be put to a vote -- choose not to vote."
The head of Italy's Radical Party, one of the main promoters of the referendum to change the law, criticised the Pope.
"We are faced with an unprecedented offensive that aims to put Italian democracy under Vatican control," said party secretary Daniele Capezzone.
"No one is saying the Church cannot have its opinion on this but the Church hierarchy cannot be allowed to hold electoral campaigns that interfere with the voting process of a country that is supposed to be sovereign," he said.
Capezzone urged Italy's president to make a statement defending the separation of Church and state.
Even some critics of the complex law say it should be fine-tuned by parliament not changed in the heat of a popular referendum.