Vatican City -
The Roman Catholic Church will roll out the red carpet for world leaders and crowned heads attending the inauguration mass on Tuesday of Pope Francis as he embarks on a ground-breaking papacy.
The occasion promises to contrast with the pomp and circumstance normally associated with grand Church occasions given the disarmingly humble style the new pope has shown in his first few days as the first Latin American leader of the world's 1.2 billion Catholics.
An event that poses an inevitable protocol headache for the Vatican - no official invitations are involved, and some VIPs may turn up unannounced - will also be a first test of the former Buenos Aires archbishop's ability to navigate choppy diplomatic waters.
German Chancellor Angela Merkel, Spanish Prime Minister Mariano Rajoy and his French counterpart Jean-Marc Ayrault are among key European leaders expected to attend, along with EU President Herman Van Rompuy and European Commission head Jose Manuel Barosso.
US Vice-President Joe Biden, a practising Catholic, arrived late on Sunday to represent Washington at the event precipitated by the shock resignation of Francis's predecessor Benedict XVI.
Argentine President Cristina Kirchner, with whom the former Jorge Mario Bergoglio, as Buenos Aires archbishop, has had tense relations because of opposing views on homosexuality and birth control, is also already in Rome.
Upon Bergoglio's surprise election as pontiff, Kirchner tersely wished him a “fruitful pastoral mission”, noting that he had “tremendous responsibility on his shoulders, seeking justice, equality, brotherhood and peace among mankind.”
Kirchner, who arrived Sunday according to the ANSA news agency, will have a face-to-face meeting with the pontiff on Monday, the Vatican said.
Another potentially difficult presence will be that of Zimbabwean President Robert Mugabe, who is under a travel ban by the European Union but is diplomatically entitled to travel to the sovereign city state of the Holy See.
Mugabe, who has been widely condemned for human rights abuses in his southern African country, visited the Vatican in May 2011 for the beatification of the late pope John Paul II.
In 2005, he attended John Paul II's funeral on a visit that drew controversy after Britain's Prince Charles shook hands with him.
The new pope also faces a diplomatic minefield with the planned attendance of Taiwanese President Ma Ying-jeou, which sparked an angry response from Beijing.
China, which bitterly opposes any steps that imply recognition of Taiwan by other countries, has also long had strained relations with the Vatican in a dispute about authority over Catholics in the country.
In 2005 Taiwan's then president Chen Shui-bian attended John Paul II's funeral.
As expected, Francis is attracting a heavyweight turnout from Latin America, home to two in five of the world's Catholics, although he has urged his compatriots to save their money and make donations to the poor instead of travelling.
Brazilian President Dilma Vana Rousseff Linhares arrived in Rome on Sunday, while Mexican President Enrique Pena Nieto, Uruguay's Vice President Danilo Astori and Colombian former president Cesar Gaviria are also expected.
Likely royalty guests include King of the Belgians Albert II and Queen Paola, Luxembourg's Grand Duke Henri and Grand Duchess Maria Teresa and Britain's Duke of Gloucester.
The first meeting between the new leaders of the Catholic and Anglican churches - Francis and Archbishop of Canterbury Justin Welby - will have to wait, however.
Welby will miss the inauguration mass because he will be on a “pilgrimage of prayer” in Britain, his office announced Sunday.
Welby, who wished Pope Francis “every blessing” following his election, will be represented at the ceremony by one of the Anglican world's leading figures, the Archbishop of York John Sentamu.
Ibrahim Isaac Sidrak, the Coptic Catholic Patriarch of Alexandria, Egypt, will also be on hand, as well as Metropolitan Hilarion, second in the Russian Orthodox hierarchy, ANSA said.
The mass, expected to attract hundreds of thousands to Rome - authorities say they are planning for up to one million - will fall on the feast day of St Joseph, the patron saint of the Universal Church.
The capacity of the vast square is only about 50 000, with more than 100 000 more expected to fill the Via della Conciliazione leading up to the square, taking in the event with the aid of giant video screens. - Sapa-AFP