The Vatican condemned same-sex unions as deviant and a threat to society yesterday in a fresh attempt to halt the growing momentum towards legalising gay marriage in North America and Europe. The Holy See urged Catholic lawmakers to vote against bills that would recognise gay marriage in a strongly worded document approved by Pope John Paul - causing anger among gay rights activists across Europe.

"Marriage exists solely between a man and a woman... Marriage is holy, while homosexual acts go against the natural moral law," said the 12-page document by the Vatican's Congregation for the Doctrine of the Faith.

"Legal recognition of homosexual unions or placing them on the same level as marriage would mean not only the approval of deviant behaviour... but would also obscure basic values which belong to the common inheritance of humanity."

The document also denounced gay couples adopting children: "Allowing children to be adopted by persons living in such unions would actually mean doing violence to these children."

Gay rights groups were swift to hit back. "This is just the latest move in their homophobic crusade," said Franco Grillini, an Italian lawmaker and honorary chairman of Arcigay, the country's largest gay rights group.