Papal 'cohabitation' poses unique Vatican challenge

Nevertheless, Lombardi said the octogenarian's presence would be felt and "appreciated", and did not rule out an advisory role for the future pensioner, whose title has yet to be determined but may be Bishop of Rome Emeritus.

The Roman Catholic Church faces a unique challenge starting next month when a living former pope begins a "cohabitation" with his successor, both residing in the world's tiniest sovereign state, Vatican City.

The Vatican insists that the German pope, who stunned the world by announcing that he will retire on February 28, wants to keep a low profile in retirement.

"He will live at the Vatican in total discretion," Vatican spokesman Federico Lombardi said Wednesday. "His presence will in no way be an impediment, interference or a problem."

Nevertheless, Lombardi said the octogenarian's presence would be felt and "appreciated", and did not rule out an advisory role for the future pensioner, whose title has yet to be determined but may be Bishop of Rome Emeritus.

"If his successor wants advice from him he will be totally free to provide it... (but) this would in no way be required" of the former pope, Lombardi said.

Others in the Vatican are more nervous about the unprecedented situation.

Rino Fisichella, head of the Vatican department for the new evangelization, said the former pope may eventually have to live elsewhere.

The Vatican on Wednesday denied an Internet rumour that the pope would take up permanent residence in the Abbey of Monte Cassino -- a famous monastery that was destroyed in World War II and rebuilt.

The cerebral former theology professor, who will turn 86 in April, is a prolific writer. He is currently completing a work on faith that started out as an encyclical but will have to be published as a book given Benedict's imminent abdication.

He is also expected to spend more time with his beloved cats and playing Beethoven and Mozart compositions on his piano.

An early signal of Benedict's intention to go quietly is his plan to leave the Vatican the day he steps aside, slipping away to the summer papal residence of Castel Gondolfo outside Rome.

The Vatican has been unable to say how long he will stay there, but has stressed he will not have any role in the Conclave of Cardinals that is to elect his successor in the third week of March -- in time for Easter at the end of the month.

His absence will allow workers to prepare the papal apartments in the Apostolic Palace for the new pontiff -- and complete renovations of the living quarters for the soon-to-be ex-pope in a former nunnery at the Vatican.

Benedict's choice not to return to his native Bavaria should surprise no one given that he has now lived in Rome for nearly four decades.