* Vatican citizenship, residence will keep "ex-pope" immune
* Vatican wants pope to be safe; easier to provide security
* Home outside Vatican could have become pilgrimage site
By Philip Pullella
VATICAN CITY, Feb 15 (Reuters) - Pope Benedict's decision to live in the Vatican after he resigns will provide him with security and privacy. It will also offer legal protection from any attempt to prosecute him in connection with sexual abuse cases around the world, Church sources and legal experts say.
"His continued presence in the Vatican is necessary, otherwise he might be defenceless. He wouldn't have his immunity, his prerogatives, his security, if he is anywhere else," said one Vatican official, speaking on condition of anonymity.
"It is absolutely necessary" that he stays in the Vatican, said the source, adding that Benedict should have a "dignified existence" in his remaining years.
Vatican sources said officials had three main considerations in deciding that Benedict should live in a convent in the Vatican after he resigns on Feb. 28.
Vatican police, who already know the pope and his habits, will be able to guarantee his privacy and security and not have to entrust it to a foreign police force, which would be necessary if he moved to another country.
"I see a big problem if he would go anywhere else. I'm thinking in terms of his personal security, his safety. We don't have a secret service that can devote huge resources (like they do) to ex-presidents," the official said.
Another consideration was that if the pope did move permanently to another country, living in seclusion in a monastery in his native Germany, for example, the location might become a place of pilgrimage.
This could be complicated for the Church, particularly in the unlikely event that the next pope makes decisions that may displease conservatives, who could then go to Benedict's place of residence to pay tribute to him.
"That would be very problematic," another Vatican official said.
The final key consideration is the pope's potential exposure to legal claims over the Catholic Church's sexual abuse scandals.
In 2010, for example, Benedict was named as a defendant in a law suit alleging that he failed to take action as a cardinal in 1995 when he was allegedly told about a priest who had abused boys at a U.S. school for the deaf decades earlier. The lawyers withdrew the case last year and the Vatican said it was a major victory that proved the pope could not be held liable for the actions of abusive priests.
Benedict is currently not named specifically in any other case. The Vatican does not expect any more but is not ruling out the possibility.
"(If he lived anywhere else) then we might have those crazies who are filing lawsuits, or some magistrate might arrest him like other (former) heads of state have been for alleged acts while he was head of state," one source said.
Another official said: "While this was not the main consideration, it certainly is a corollary, a natural result."
After he resigns, Benedict will no longer be the sovereign monarch of the State of Vatican City, which is surrounded by Rome, but will retain Vatican citizenship and residency.
That would continue to provide him immunity under the provisions of the Lateran Pacts while he is in the Vatican and even if he makes jaunts into Italy as a Vatican citizen.
The 1929 Lateran Pacts between Italy and the Holy See, which established Vatican City as a sovereign state, said Vatican City would be "invariably and in every event considered as neutral and inviolable territory".
There have been repeated calls for Benedict's arrest over sexual abuse in the Catholic Church.
When Benedict went to Britain in 2010, British author and atheist campaigner Richard Dawkins asked authorities to arrest the pope to face questions over the Church's child abuse scandal.
Dawkins and the late British-American journalist Christopher Hitchens commissioned lawyers to explore ways of taking legal action against the pope. Their efforts came to nothing because the pope was a head of state and so enjoyed diplomatic immunity.
In 2011, victims of sexual abuse by the clergy asked the International Criminal Court to investigate the pope and three Vatican officials over sexual abuse.
The New York-based rights group Center for Constitutional Rights (CCR) and another group, Survivors Network of those Abused by Priests (SNAP), filed a complaint with the ICC alleging that Vatican officials committed crimes against humanity because they tolerated and enabled sex crimes.
The ICC has not taken up the case but has never said why. It generally does not comment on why it does not take up cases.
NOT LIKE A CEO
The Vatican has consistently said that a pope cannot be held accountable for cases of abuse committed by others because priests are employees of individual dioceses around the world and not direct employees of the Vatican. It says the head of the church cannot be compared to the CEO of a company.
Victims groups have said Benedict, particularly in his previous job at the head of the Vatican's doctrinal department, turned a blind eye to the overall policies of local Churches, which moved abusers from parish to parish instead of defrocking them and handing them over to authorities.
The Vatican has denied this. The pope has apologised for abuse in the Church, has met with abuse victims on many of his trips, and ordered a major investigation into abuse in Ireland.
But groups representing some of the victims say the Pope will leave office with a stain on his legacy because he was in positions of power in the Vatican for more than three decades, first as a cardinal and then as pope, and should have done more.
The scandals began years before the then-Cardinal Joseph Ratzinger was elected pope in 2005 but the issue has overshadowed his papacy from the beginning, as more and more cases came to light in dioceses across the world.
As recently as last month, the former archbishop of Los Angeles, Cardinal Roger Mahony, was stripped by his successor of all public and administrative duties after a thousands of pages of files detailing abuse in the 1980s were made public.
Mahony, who was archbishop of Los Angeles from 1985 until 2011, has apologised for "mistakes" he made as archbishop, saying he had not been equipped to deal with the problem of sexual misconduct involving children. The pope was not named in that case.
In 2007, the Los Angeles archdiocese, which serves 4 million Catholics, reached a $660 million civil settlement with more than 500 victims of child molestation, the biggest agreement of its kind in the United States.
Vatican spokesman Father Federico Lombardi said the pope "gave the fight against sexual abuse a new impulse, ensuring that new rules were put in place to prevent future abuse and to listen to victims. That was a great merit of his papacy and for that we will be grateful". (Reporting by Philip Pullella; Additional reporting by Robin Pomeroy; Edited by Simon Robinson and Giles Elgood)