Pope Benedict has revealed that he may become the first Pope to voluntarily resign in more than 700 years should he become physically or mentally incapacitated.

The papacy has traditionally been seen as a job for life, with pontiffs expected to remain at the helm of the Church until they die.

In a book of interviews, the 83-year-old Pontiff challenged centuries of Catholic Church tradition by saying that he would not hesitate to relinquish his post if he no longer felt "physically, psychologically and spiritually" up to the job.

The last pope to resign willingly was Celestine V in 1294 after reigning for only five months. Gregory XII reluctantly abdicated in 1415 to end a dispute with a rival claimant to the Holy See.

But in the book, 'Light of the World: The Pope, the Church, and the Sign of the Times', Benedict said: "Yes, if a pope clearly realises that he is no longer physically, psychologically and spiritually capable of handling the duties of his office, then he has a right and, under some circumstances, also an obligation, to resign."

With startling candour, the 83-year-old introduced the possibility of something Catholic Church officials do not like to talk about because it could open a doctrinal can of worms.

The book, an interview with German Catholic journalist Peter Seewald, also contains personal reflections on the Pope's health and daily routine.

Earlier this year, when the Vatican was swept up by a new wave of sexual abuse scandals, there were calls for Pope Benedict to step down, but he says in the book that he would not "run away" in a time of crisis.

"One can resign at a peaceful moment or when one simply cannot go on," he says.

Pope Benedict seems to be in relatively good health, but confesses in the book that he feels his forces diminishing.

"Of course, I am sometimes concerned and I wonder whether I can make it even from a purely physical point of view," he says of the demand on his strength during trips.

"The Holy Father is aware of his work and his complete dedication for the good of the Church," said newly appointed Cardinal Raul Eduardo Vela Chiriboga of Ecuador. "If something serious happens to his health it is logical that he would consider, with all the responsibility he has, what to do."

There is a provision in canon law for the resignation of a pope but it has never been used. It says a pope can resign but has do it of his own free choice and it does not have to be accepted.

Belfast Telegraph