Pope John Paul on Monday told Spain's new Socialist prime minister, whose government plans to legalise gay marriage, that Spain had to conserve ethical and moral values rooted in its Christian culture.
Jose Luis Rodriguez Zapatero made a special, lightning trip to Rome to see the 84-year-old pontiff.
The fact he had no meetings with Italian leaders underscored the importance Spain's first Socialist government in eight years attaches to relations with the Vatican despite its policies.
The two spoke privately for about 15 minutes before the pope read a public address to Zapatero in which he made two clear references to moral issues.
The Polish pontiff said Spain had to "conserve moral and cultural values, as well as its Christian roots".
He also said he hoped the Spanish government would "give due attention to ethical values that are so rooted in the religious and cultural tradition of the population".
The move to legalise homosexual marriages, which Zapatero announced two months ago, has stirred controversy in one of Europe's most Catholic countries. Homosexuality was only made legal in Spain after the death of dictator Francisco Franco in 1975.
The pope and the Catholic Church have repeatedly condemned moves in several European countries and Massachusetts in the United States to legalise gay marriage.
Zapatero sought to assure the pope the government would not revise a 1979 Church-state agreement which grants special benefits to the Roman Catholic Church.
There had been talk in Spain that the new government might seek to change the so-called Concordat as well as modify legislation aimed at speeding up divorce proceedings.
Speaking to reporters just off St Peter's Square after leaving the Vatican, Zapatero said the visit had been very cordial and friendly.
Asked if any legislative changes were on the horizon, he said: "No, the strategy is to keep existing accords in effect and maintain an open relationship with the Vatican."
The prime minister said he and the pope discussed the future of the European Union. On Sunday the pope expressed dismay over EU failure to mention Christianity in its new constitution.
Zapatero told reporters he and the pope discussed the international situation, particularly the Middle East, but not Iraq specifically.
Both the pope and Zapatero opposed the war in Iraq and Zapatero recalled Spanish troops from the country shortly after his party won power.