Pope Francis' diplomatic skills are being tested in
his first audience with a visiting head of state, Argentine president
Cristina Fernandez, with whom he clashed over her socially liberal
policies.Ms Fernandez will call on the former Archbishop of Buenos Aires at his makeshift home, the Vatican hotel on the edge of the Vatican gardens, a day before she and other world leaders attend his installation Mass in St Peter's Square.
She and her predecessor and late husband Nestor Kirchner defied church teaching to adopt a series of measures with popular backing, including mandatory sex education in schools, free distribution of contraceptives in public hospitals, and the right for transsexuals to change their official identities on demand.
Argentina was the first Latin American country to legalise same-sex marriages.
Meanwhile Zimbabwe's president Robert Mugabe arrived in Rome for the inaugural mass.
Mugabe is the subject of a travel ban by European nations in protest at his human rights record in a decade of political and economic turmoil, but it does not affect his trips to the Vatican through Italy or United Nations meetings elsewhere.
A practising Catholic, Mugabe, 89, joined world leaders at the 2005 funeral of Pope John Paul II who visited Zimbabwe on an African pilgrimage in 1988.
At the Pope's request then, Zimbabwe suspended criminal executions but hangings resumed nearly a decade later.