Pope Benedict XVI's tumultuous years: key dates

Pope Benedict XVI, who on Monday announced he will resign on February 28, has lived through almost eight tumultuous years as pontiff since his election on April 19, 2005.

Here are some key dates of a pontificate marked by strained inter-faith relations and a series of paedophile priest scandals:

-- September 12, 2006: Benedict angers Muslims worldwide by quoting a Byzantine emperor who linked Islam and violence in a lecture at the University of Regensburg, Germany, where he previously taught theology.

The lecture sparked days of at times violent protests in Muslim countries, prompting the pontiff to say that he was "deeply sorry" for any offence and attributing the outrage to an "unfortunate misunderstanding".

-- November 30, 2006: The pope reaches out to Muslims during a visit to Turkey, assuming an attitude of Muslim prayer while facing Mecca in Istanbul's Blue Mosque.

-- July 19, 2008: Benedict issues a historic full apology to victims of child sex abuse by clergy during a visit to Australia, meeting with four victims two days later.

In April 2008, the pope had already met with abuse victims during a trip to the United States.

-- January 24, 2009: Benedict lifts the excommunication of breakaway traditionalist bishops including Richard Williamson, who claimed there were never Nazi gas chambers and that the Nazis killed up to 300,000 Jews -- not six million.

Criticism from Jewish groups, German Chancellor Angela Merkel and from within the Catholic Church forces the Vatican to demand that Williamson "unequivocally and publicly" change his views before he can be fully readmitted into the Catholic fold.

-- March 17, 2009: The pontiff says distributing condoms in the fight against AIDS "can aggravate the problem" while aboard his plane en route to Africa, the continent worst hit by the disease.

-- May 15, 2009: He concludes a trip to the Holy Land, during which he visited Israel, Jordan and the Palestinian Territories, by calling for a two-state solution to end Middle East wars and "terrorism" and slams the Holocaust as "brutal extermination".

-- March 20, 2010: Benedict issues a pastoral letter to Irish Catholics expressing "shame" and "remorse" over paedophile priests and rebukes the Irish Church after explosive government reports reveal systematic cover-ups by the hierarchy.

The crisis in Ireland, which broke out in November 2009, is followed by an avalanche of similar scandals in Europe and the United States.

-- May 1, 2011: Benedict bestows the status of "blessed" on his predecessor John Paul II in front of a million people in a ceremony that puts the late pope one step away from sainthood.

-- May 18, 2011: He calls on Catholics across the world to pray that Chinese bishops refuse to separate from Rome, in spite of "pressure" from communist authorities.

- September 15, 2012: During a visit to Lebanon, the Pope urges Middle Eastern Christians and Muslims should forge a harmonious, pluralistic society in which the dignity of each person is respected and the right to worship in peace is guaranteed.

-- December 22, 2012: Benedict pardons and frees his former butler but banishes him from the Vatican, 12 months after Paolo Gabriele leaked secret papal memos revealing a series of alleged fraud scandals in the Vatican. The embarrassment is called the "Vatileaks" scandal.