By Christian Fraser
BBC News, Rome
Hummes: Seen by some as potential pontiff
The cardinal who is taking over the Vatican office in charge of priests says the Catholic Church might one day have to review the issue of celibacy.
Cardinal Claudio Hummes told a newspaper in his native Brazil that celibacy was not a prescribed doctrine.
Rather, he said, it was a discipline which priests imposed on themselves.
The statement comes two weeks after the Vatican reaffirmed it would not allow priests to marry. The number of men becoming priests has been falling.
The question many in the church are asking is whether the demand the Vatican makes on its priests - to be chaste and celibate - is forcing young men to ignore the calling.
Discipline not dogma
Cardinal Hummes, who takes over the Congregation for the Clergy this month - and he must try in his new role to re-energise the seminary - believes there is a debate to be had.
Celibacy is a discipline, he said, it is not a dogma of the Church.
Certainly, the majority of the apostles were married and in the early Christian Church many priests, and at least one pope, Hadrian II, had wives. In this modern age the Church must observe these things; it has to advance with history.
The 72-year-old cardinal is viewed by some as a potential successor to Pope Benedict.
His comments will be taken seriously.
But two weeks ago, senior figures in the Vatican met for three hours to discuss this issue and they reaffirmed the need for solid Christian and human training.
Correction 10 November 2008: Earlier versions of this story wrongly stated that many popes had wives and also that there was no formal ban on marriage for the clergy in the Middle Ages. Amendments were made following a ruling by the BBC's Editorial Complaints Unit.