(AP) - Pope Benedict XVI, centre right meets Bolivia's President Evo Morales, during a private audience in the pontiff's studio, at the Vatican, Monday, May, 17, 2010. (AP Photo/Andrew Medichini, Pool)

(Reuters) - Pope Benedict XVI waves next to Cardenal Tarcisio Bertone at the end of an outdoor mass in the Avenida dos Aliados square in Porto, northern Portugal May 14, 2010. The Pope is in Portugal on a four-day pastoral visit. REUTERS/Jose Manuel Ribeiro (PORTUGAL - Tags: RELIGION)

(Reuters) - Pope Benedict XVI walks past a mural during a mass at the Catholic shrine of Fatima in central Portugal, May 13, 2010. Thousands of pilgrims made their way to the Fatima Shrine to attend a mass by Pope Benedict XVI to mark the 93rd anniversary celebrations of the first appearance of the Virgin Mary to three shepherd children in 1917. REUTERS/Jose Manuel Ribeiro (PORTUGAL - Tags: RELIGION SOCIETY ANNIVERSARY)

(Reuters) - Pope Benedict XVI looks on during a visit to the Belem cultural centre in Lisbon, May 12, 2010. Pope Benedict said on Tuesday that the greatest threat to Catholicism came from "sin within the Church", one if his most forthright comments so far on a sexual abuse scandal that has created turmoil in the church. The Church has "a very deep need" to recognise that it must do penitence for its sins and "accept purification", he said. REUTERS/Stefano Rellandini (PORTUGAL - Tags: RELIGION)

(Reuters) - People wait for the arrival of Pope Benedict XVI outside Lisbon's Jeronimos Monstery at the start of his four-day pastoral visit to Portugal May 11, 2010. May 11, 2010. REUTERS/Nacho Doce (PORTUGAL - Tags: RELIGION POLITICS)

(Reuters) - Pope Benedict XVI leads the Angelus prayer from a window of his private apartment at the Vatican March 9, 2010. REUTERS/Stefano Rellandini (ITALY - Tags: RELIGION)

(AP) - FILE - In this March 2, 2009 file picture Walter Mixa, Catholic Bishop of Augsburg, waits for the beginning of the Spring Assembly of the German Bishop's Conference in Hamburg, northern Germany. The leading bishop from Pope Benedict's XVI's German homeland who is being investigated by prosecutors for alleged sex abuse of his post Saturday May 8, 2010, the latest casualty of the pontiff's housecleaning of prelates stained by accusations of molesting minors. Benedict formally accepted the resignation offer made April 21 by Bishop Walter Mixa, an outspoken conservative voice in the German church and a military chaplain for Germany, as well as head of the Augsburg diocese. Mixa is also under probe for alleged financial misconduct at a children's home under his direction. He had admitted slapping children decades ago when he was a priest, but his lawyer has denied press reports prosecutors are investigating him on a sexual abuse complaint. (AP Photo/Focke Strangmann,File)

(Reuters) - Portuguese artist Albuquerque Mendes shows a medal he designed for Pope Benedict's visit to Portugal, in Lisbon April 28, 2010. Pope Benedict XVI will visit Portugal from May 11 to May 14. Picture taken April 28, 2010. REUTERS/Jose Manuel Ribeiro (PORTUGAL - Tags: RELIGION)

(AFP/File) - Cardinal Sean Brady, Archbishop of Armagh and Primate of All Ireland, at a press conference nearby a portrait of Pope Benedict XVI. Brady, the current head of the Catholic Church in the country, has faced calls to resign after it emerged that he had required two abused children to sign an oath of silence.(AFP/File/Christophe Simon)

(AP) - FILE - In this April 7, 2010 file photo, Pope Benedict XVI, listens to his personal secretary Georg Gaenswein during the weekly general audience in St. Peter's Square, at the Vatican. The Vatican goes into full-fledged damage control mode in the priest sex abuse scandal ahead of the pope's first foreign trip since it erupted. (AP Photo/Pier Paolo Cito, File)

(AFP/File) - Pope Benedict XVI celebrates mass in St. Peter's Basilica in the Vatican. The Catholic leadership has been thrown on the defensive by scandals which have erupted in Ireland, Austria, the United States and the pope's native Germany in recent months.(AFP/File/Filippo Monteforte)

(Reuters) - A May 25, 2006 file photo shows Poland's President Lech Kaczynski looking on as Pope Benedict XVI waves to the crowd outside the presidential palace in Warsaw. Kaczynski was killed when a plane carrying 132 people crashed in thick fog on its approach to a Russian airport on April 10, 2010, killing everyone on board, officials said. REUTERS/Maxi Rossi/Files (POLAND - Tags: POLITICS RELIGION OBITUARY DISASTER TRANSPORT)

(AFP/File) - Members of the US Survivors Network of those Abused by Priests hold up a picture of Pope Benedict XVI on March 25, 2010 as they take part in a demonstration against child sexual abuse, in front of St. Peter's Square at the Vatican.(AFP/File)

(Reuters) - Pope Benedict XVI embraces Italian cardinal Angelo Sodano as he leads the Easter mass in Saint Peter's Square at the Vatican April 4, 2010. REUTERS/Alessandro Bianchi

(Reuters) - Pope Benedict XVI waves to the faithful as he leaves after his weekly audience in St. Peter's Square at the Vatican March 31, 2010. REUTERS/Alessia Pierdomenico

(Reuters) - A believer holds palm as Pope Benedict XVI leads the Palm Sunday mass in Saint Peter's Square at the Vatican March 28, 2010. REUTERS/Alessandro Bianchi (VATICAN - Tags: RELIGION)