Prime Minister Renzi would have had to resign had he lost Thursday's vote, but 173 members voted for the bill as compared to the 71 who were against it.

However, the planned law did not give same-sex couples the right to get married or to adopt children. Changes in the bill included dropping the word "faithfulness," which could be misconstrued as equivalent to marriage. The Catholic Church considers marriage to be a union only between a man and a woman.

Members of parliament were also split over the right to adoption. Several leaders close to the Catholic Church said the "stepchild" adoption clause would encourage gay couples to have babies with surrogate mothers, which is illegal in Italy.

Italy is one of the few major countries not to have recognized civil unions legally. The bill was introduced in parliament after several years and following a statement by the European Court of Human Rights, which condemned Rome for failing to provide most basic laws to gays, including inheritance rights and recognition of the civil union.

But despite Prime Minister Renzi calling the bill "historic," rights groups denounced the decision to leave out the adoption provision. "The text once again does not take into consideration children who need definite laws and protection," Flavio Romani, chief of the gay rights group Arcigay told journalists: "The law that has come out of all this is lacking its heart."

Interior Minister Angelino Alfano, who leads the New Center Right party (NCD), said Italy had "prevented a revolution that went against nature" by preventing gays the right to adoption.

The legislation now has to pass the lower Chamber of Deputies. Debate on it is being keenly watched in Italy, where the Vatican influences both politics and society.

mg/sms (Reuters, AP)