Pope Benedict renewed his attack on gay marriage on Saturday, saying Christians must defend traditional heterosexual marriage as a "pillar of humanity" benefiting both believers and non-believers.
Calling on the faithful to stand up for traditional notions of marriage and procreation in the face of moves to recognise gay marriage, he said: "Such a witness can only stimulate politicians and legislators to safeguard the rights of the family.
"It's well known that legal solutions like so-called 'civil unions' are gaining ever greater acceptance, even if, while they exclude the responsibilities of marriage, they claim the same rights," he said in a speech to the Ponitifical Council for the Family.
"Sometimes, there is the wish even to change the definition of marriage to legalise homosexual unions, granting them the right to adopt children."
The comments are stronger than remarks Benedict made two days ago which were criticised by some members of Italy's incoming centre-left government as unwanted interference in a political issue.
"The Church's interventions (on gay couples) are now becoming daily and really do represent a crusade on parliament and lawmakers, aimed at blocking any discussion of the rights of new couples," said Franco Grillini, a member of parliament of the Democrats of the Left and honorary chairman of Italy's gay rights movement Arcigay.
Centre-left leader Romano Prodi, who is due to be appointed prime minister next week, included in his election manifesto a promise to legally recognise civil unions, stopping short of introducing gay marriage and not allowing same-sex couples to adopt.