VATICAN CITY - The Vatican urged Catholics and non-Catholics on Thursday to unite in campaigning against gay marriages and gay adoptions, seeking to stem the widening legal recognition of same-sex unions.

Catholic politicians have a "moral duty" to oppose laws granting legal rights to gay couples, and non-Catholics should follow their lead since the issue concerns "natural moral law," said the Vatican's orthodoxy watchdog, the Congregation for the Doctrine of the Faith.

The 12-page document, issued in seven languages, was criticized by gay groups across North America and Europe, where politicians are increasingly granting homosexual couples the same legal status as heterosexual couples.

"This new document is intended to intimidate public officials across the globe into doing what the Vatican has not been able to do on its own - stem the growing tide for justice," said Marianne Duddy, executive director of Dignity USA, an organization of gay Catholics. "It is a tremendous shame that the leaders of our Church are becoming the vocal proponents for intolerance and continuing discrimination."

But the document was welcomed by some conservatives, including in Pope John Paul II's native Poland, where Roman Catholic bishops read excerpts at a news conference to condemn a proposal by leftist lawmakers to legalize homosexual unions.

"The idea is immoral and hurting to families and marriages," said Bishop Stanislaw Stefanek. "We strongly object to it."

The document, "Considerations Regarding Proposals to Give Legal Recognition to Unions Between Homosexual Persons," sets out a battle plan for politicians confronted with legislation legalizing same-sex unions and rails against gay adoption.

Gay adoptions "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 human development," it said.

The document calls on Catholic politicians to vote against laws granting legal recognition to homosexual unions and to work to repeal those already on the books.

"To vote in favor of a law so harmful to the common good is gravely immoral," it said, although it didn't specify penalties for Catholics who do.

Canadian Prime Minister Jean Chretien, who is Catholic, has supported a proposed law that would define marriage as a union between two people, rather than a man and a woman.

"The Prime Minister has said on numerous occasions that it's important that there's a separation between the church and the state. It was with this view that the legislation was drafted, and it's with the same view that he'll be voting on the legislation," said Thoren Hudyma, spokeswoman for Chretien.

She quoted the proposed law as saying: "Nothing in this Act affects the freedom of officials of religious groups to refuse to conduct marriage ceremonies that are not in accordance with their religious beliefs."

In June, an appeals court in Ontario ruled that Canada's definition of marriage as between a man and a woman was unconstitutional, paving the way for legalized gay unions.

In the United States, Vermont has a "civil union" law, giving same-sex couples the rights of traditional marriages, and the highest court in Massachusetts is weighing whether to legalize such unions.

Some Republican lawmakers are calling for a constitutional amendment that would ban gay marriages nationwide.

On Wednesday, U.S. President George W. Bush told a news conference marriage was strictly a union between a man and a woman and that he wants to "codify that, one way or the other." Government lawyers are exploring measures to enshrine it into law, the White House said.

In the past two years, the Netherlands and Belgium extended marriage rights to all couples, no matter the partners' gender. Germany, France, Sweden and Denmark also have "civil union" laws.

In the Netherlands and Belgium, the proposals were backed by conservative Christian Democrat parties.

"It's the Vatican's good right to make statements like this, but here in the Netherlands, we have separation of church and state," said Kathleen Ferrier, a spokeswoman for the Christian Democrats.

In Belgium, where three-quarters of the population is Roman Catholic, the Flemish Christian Democrats said the issue boiled down to supporting all kinds of families.

"For us, what's important is sustained relationships," said Luk Vanmaercke, a party spokesman.