VATICAN CITY — Pope Francis’ diplomatic skills were tested Monday as his political nemesis, Argentine President Cristina Fernandez, asked him to intervene in the dispute with Britain over the Falkland Islands.
There was no immediate comment from the Vatican as to whether the Argentine-born Francis would accept her request, which was made during his inaugural audience with a visiting head of state on the eve of his installation as pope.
Francis and Fernandez are longtime rivals: As leader of Argentina’s Catholics, he had accused her populist government of demagoguery, while she called his position on gay adoptions reminiscent of the Middle Ages and the Inquisition.
But where the Falklands are concerned, Francis has been quoted as saying that Britain ‘‘usurped’’ the remote islands, which Argentina claims and calls the Malvinas.
Argentina and Britain fought a 1982 war over the islands. Earlier this month, the islanders voted overwhelmingly to remain a British territory.
Fernandez told journalists Monday after having lunch with the pope that she had asked for Francis’ intercession to ‘‘facilitate dialogue’’ with Britain over the islands.
Last week, British Prime Minister David Cameron said he didn’t agree with Francis’ views on the Falklands.
In asking Francis to intervene, Fernandez said she recalled how Pope John Paul II averted war in 1978 between Argentina and Chile over three tiny islands in the Beagle Channel at the southern tip of South America. With military governments on both sides poised for battle, he sent his personal envoy to mediate the crisis through shuttle diplomacy between Santiago and Buenos Aires, and eventually brought both governments to the Vatican to consider his compromise.
The conflict wasn’t entirely resolved until after democracy returned to Argentina and both sides signed a ‘‘treaty of peace and friendship’’ at the Vatican in 1984, giving the islands to Chile but maritime rights to Argentina.
On Monday, Fernandez gave Francis a picture of a marble monument honoring the 30th anniversary of John Paul II’s negotiations, and then used the opportunity to bring up the issue of sovereignty over the Falklands.
They also seemed to have patched up their relationship.
Fernandez gave the new pope a mate gourd and straw, to hold the traditional Argentine tea that Francis loves, and he gave her a kiss.
‘‘Never in my life has a pope kissed me!’’ Fernandez said afterward.
Fernandez and her predecessor and late husband, Nestor Kirchner, defied church teaching to push through a series of measures with popular backing in Argentina, including mandatory sex education in schools, and free distribution of contraceptives in public hospitals.
Fernandez called on the former Archbishop of Buenos Aires at his temporary home, the Vatican hotel on the edge of the Vatican gardens, and the two later had lunch together, a day before she and other world leaders attend his installation Mass in St. Peter’s Square that some estimates say could bring 1 million people to Rome.
The Vatican on Monday released details of the Mass, saying it would be a simplified version of the 2005 installation Mass that brought Pope Benedict XVI to the papacy, with many gestures to Eastern rite Catholics and Orthodox Christians in a sign of church unity.
More than 132 government delegations will descend on Rome for the Mass installing Francis as the 266th leader of the 1.2-billion strong Catholic Church. Authorities are planning for about 1 million people to attend the Mass, numbers not seen since the beatification of Pope John Paul II in 2011, which drew 1.5 million.
Among the dignitaries at the Mass will be the spiritual leader of the world’s Orthodox Christians, Ecumenical Patriarch Bartholomew I. His presence at the installation is the first from the Istanbul-based Patriarchate in nearly 1,000 years since the Great Schism divided the church in 1054.
During the Mass, the Gospel will be chanted in Greek as opposed to Latin and eastern rite prelates will join Francis at an initial prayer at the tomb of St. Peter under the basilica’s main altar, the Vatican said.
In all, some 33 Christian delegations will be present, as well as representatives of Jewish, Muslim, Buddhist, Sikh, and Jain communities.
The Vatican also released details of Francis’ coat of arms and official ring, both of which are in keeping with his simple style and harking back to popes past: The coat of arms is the same Jesuit-inspired one he used as archbishop of Buenos Aires, while the ring was once offered to Pope Paul VI.
Francis will officially receive the ring and the pallium, a wool stole, during Tuesday’s installation Mass, which is drawing six sovereign rulers, 31 heads of state, three princes and 11 heads of government to the Vatican. Vice President Joe Biden, who is Catholic, will represent the United States at the ceremony. The delegation also includes Susana Martinez, the governor of New Mexico; Representative Nancy Pelosi, the Democratic leader of the House of Representatives; and Dr. John J. DeGioia, the president of Georgetown University, a Jesuit institution.