The pope spoke Saturday to the new Canadian Ambassador to the Holy See, Donald Smith.

"The institution of marriage necessarily entails the complementarity of husbands and wives who participate in God's creative activity through the raising of children," said the pontiff, according to the text of the speech released by the Vatican.

"Spouses thereby ensure the survival of society and culture, and rightly deserve specific and categorical legal recognition by the State.

"Any attempts to change the meaning of the word 'spouse' contradict right reason: legal guarantees, analogous to those granted to marriage, cannot be applied to unions between persons of the same sex without creating a false understanding of the nature of marriage."

Three Canadian provinces, accounting for about 70 percent of the country's 31 million people, allow same-sex marriage: Quebec, Ontario and British Columbia. The ruling Liberal Party has promised legislation legalizing gay marriage, perhaps next year after Canada's Supreme Court gives a nonbinding opinion on a tentative bill.

Speaking to another newly appointed ambassador to the Holy See, Philip McDonagh of Ireland, the pope called on the European Union to keep a policy of openness and acceptance of immigrants. Ireland held the EU rotating presidency until the end of June.

"The plight of refugees and those displaced by poverty, war or persecution is particularly dramatic and calls for special consideration and generosity," John Paul said.