VATICAN CITY — Amid increasing worldwide initiatives to grant legal recognition to same-sex unions, the Vatican called on lawmakers to offer "clear and emphatic opposition" to such measures, which it said were contrary to human nature and ultimately harmful to society.

In a 12-page document released July 31, the Vatican expressed particular alarm at moves to allow gay couples to adopt children, which it said would be a form of "violence" against children and "gravely immoral."

The document rejected arguments that failing to give gay unions legal recognition would be unjust discrimination and underscored the unique social role of marriage between a man and a woman in continuing the human race and raising children.

"The denial of the social and legal status of marriage to forms of cohabitation that are not and cannot be marital is not opposed to justice; on the contrary, justice requires it," it said.

"Legal recognition of homosexual unions or placing them on the same level as marriage would mean not only the approval of deviant behavior, with the consequence of making it a model in present-day society, but would also obscure basic values which belong to the common inheritance of humanity," it said.

It instructed Catholic politicians that they were morally bound to oppose such "gravely unjust laws" and said all public servants had the right to conscientious objection if they were asked to apply them.

A note at the end of the document said it had been approved by Pope John Paul II, who ordered its publication.

Titled "Considerations Regarding Proposals to Give Legal Recognition to Unions Between Homosexual Persons" and released in Italian, French, English, German, Spanish, Portuguese and Polish, the document coincided with a growing movement in Europe and North America toward granting gay couples some or all of the legal protections and benefits of marriage.

In late July, Massachusetts' highest court was widely expected to rule in favor of legalizing same-sex marriages; similar legislation was enacted in 2000 in Vermont. Also in July, Canada's government proposed a draft bill to legalize same-sex marriage; Belgium and the Netherlands already have expanded equal marriage rights to homosexuals, and a number of other European countries offer gay couples civil-union rights.

Opposition to gay marriage, including opposition among white U.S. Catholics, has dropped significantly in recent years, according to a poll released in July by the Pew Research Center for the People and the Press. Just 41 percent of white Catholics today oppose legalized gay marriage, in contrast with 60 percent in 1996. Support for such measures among white Catholics has increased in the same period from 31 percent to 47 percent.

A day before the Vatican released its document, U.S. President George W. Bush told reporters in Washington that White House lawyers were exploring ways to ensure that "marriage" remains legally defined as a union between a man and a woman. Some U.S. lawmakers have proposed a constitutional amendment to ban same-sex marriages.

The Vatican's document went further than those proposals by rejecting any extension of special rights or legal status to homosexual couples. It said cohabiting homosexuals could use general provisions of the law to protect their rights as persons "like all citizens from the standpoint of their private autonomy."

"Not even in a remote analogous sense do homosexual unions fulfill the purpose for which marriage and family deserve specific categorical recognition," the document said.

"On the contrary, there are good reasons for holding that such unions are harmful to the proper development of human society, especially if their impact on society were to increase," it said.

In a footnote, the document warned of the "danger" that granting legal status to gay unions "could actually encourage a person with a homosexual orientation to declare his homosexuality and even to seek a partner in order to exploit the provisions of the law."

Noting that civil laws play a "very important and sometimes decisive role in influencing patterns of thought and behavior," the document said granting legal status to gay unions would expose young people, especially, to erroneous ideas about sexuality and marriage, and thus could "contribute to the spread of the phenomenon."

The document also condemned legislative moves to allow gay couples to adopt, saying that being deprived of having either a mother or a father has been shown to harm children's normal development.

"Allowing children to be adopted by persons living in such unions would actually mean doing violence to these children, in the sense that their condition of dependency would be used to place them in an environment that is not conducive to their full development," it said.

It said gay adoption is not only "gravely immoral," but also openly contradicts the U.N. Convention on the Rights of the Child, which says consideration of the best interests of the child must be paramount.

While presented as an aid to local bishops and all those who are "committed to promoting and defending the common good of society," the document offered special instruction to Catholic politicians, who it said were particularly obliged to fight efforts to legally recognize gay unions.

When such legislation is first proposed, "the Catholic lawmaker has a moral duty to express his opposition clearly and publicly and to vote against it. To vote in favor of a law so harmful to the common good is gravely immoral," it said.

In the face of already existing laws, the document said Catholic politicians must make their opposition known and work "in the ways that are possible" to repeal the law completely, or partially "when its total abrogation is not possible at the moment."

While the document called homosexuality a "troubling moral and social phenomenon," it underscored church teaching that homosexuals "must be accepted with respect, compassion and sensitivity" and that they should not be unjustly discriminated against. But, it added, "the church teaches that respect for homosexual persons cannot lead in any way to approval of homosexual behavior or to legal recognition of homosexual unions."

In Italy, the document drew immediate condemnation from gay rights groups. At St. Peter's Square July 31, a handful of protesters from Italy's Radical Party compared Catholic Church leaders to Afghanistan's former Islamic fundamentalists, holding placards that read: "No Vatican! No Taliban!"

The document can be found on the Vatican's Web site at: http://www.vatican.va/roman_curia/congregations/cfaith/documents/rc_con_cfaith_doc_20030731_homosexual-unions_en.html.