"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 February 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.