Pope Benedict XVI will on Monday mark five years at the helm of a Roman Catholic Church deep in crisis over its handling of a series of paedophile priest scandals.

The Vatican's laments of being unfairly targeted for attack, combined with statements or initiatives seen as half-measures - as well as outright gaffes - have weakened the Pontiff, analysts say.

And Pope Benedict, who turned 83 yesterday, has already built up a reputation of seeming insensitivity on other issues.

The German Pontiff has repeatedly angered Jews since his election in 2005, notably by lifting the excommunication of traditionalist bishop Richard Williamson, who insists that no there were no Nazi gas chambers.

But he has also found himself in hot water with Muslims, native Indians, Poles, gays and even scientists.

"In the modern era, there has never been a pontificate marked by such cyclical crises that have become continual by now," said Vatican expert Marco Politi of the left-wing Italian newspaper Il Fatto Quotidiano.

Of them all, the furore over child-molesting priests is by far the most damaging because "the crimes committed by many clergymen were covered by the silence of Church authorities," Mr Politi said.

"These are not isolated crimes, but an institutional sin of silence," Mr Politi said.

He praised Pope Benedict for a letter to Irish Catholics last month in which the pontiff rebuked the nation's bishops for making "serious mistakes" in responding to allegations.

However, Mr Politi said: "Because many of his choices have provoked crises, Pope Benedict has shattered the Catholic world, and today the Church is very divided, even if it doesn't really show.

"The Papacy has lost its ability to attract and the influence on public opinion that it had during the time of John Paul II," Mr Politi said.

Another Vatican watcher, John Allen of the National Catholic Reporter, said: "In terms of business management, this pontificate goes from one crisis to the other."

Pope Benedict found himself in his first full-blown crisis in September 2006 when he unleashed fury in the Muslim world with a speech in which he appeared to endorse the view of an obscure 14th-century Byzantine emperor that Islam is inherently violent.

It is with Judaism, however, that Pope Benedict has had the most frequent brushes.

In 2008, Pope Benedict allowed the revival of a Good Friday prayer "for the conversion of the Jews", which had been thrown out by Vatican II in the 1960s.

Catholic-Jewish relations improved with a series of fence-mending statements and gestures by the Vatican and the Pontiff, notably Pope Benedict's trip to Israel in May last year during which he prayed at Jerusalem's Western Wall, also known as the Wailing Wall.

But in December Jews were up in arms once again when the pope moved his World War II-era predecessor Pope Pius XII a step closer to sainthood with a decree bestowing the title "venerable."

When Pope Benedict travelled to Brazil in 2007 he made waves with his suggestion that the indigenous people had been "silently longing" for Christ, denying that European colonisers had imposed their faith on them.

And on a 2009 trip to Africa, the region hardest hit by the AIDS pandemic, the Pope angered health campaigners when he said that condom use could be aggravating the crisis.

"That was the first time Western governments officially criticised the Pope, and the Belgian Parliament even passed a motion against the Vatican," Mr Politi recalled.

Yet, Mr Allen noted that on doctrinal matters where the theologian pope excels he has produced "deep, well-written, lucid" documents including three encyclicals.

"This is a great irony: Pope Benedict does very well on what he cares most about, but that is eclipsed by the chaos in his pontificate," Mr Allen said.

Key dates of Benedict's Pontificate

September 12, 2006: Pope Benedict angers Muslims worldwide by implicitly linking Islam and violence in a lecture at the University of Regensburg, Germany, where he previously taught theology.

The lecture sparked days of sometimes 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: Pope 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 his trip to the US.

January 24, 2009: Pope 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.

March 20, 2010: Pope 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, was followed by an avalanche of similar scandals in Europe and the US.