Cardinal Pell, who was close to the Pope when both served on the key Vatican watchdog congregation and played an important role gathering support for him at the 2005 conclave at which Benedict was elected, said the resignation created a precedent and left the church in an even more uncertan position.

Cardinal Pell, Australia's only voter at the coming papal election, was unexpectedly candid in a television interview. He said: "People who, for example, might disagree with a future pope will mount a campaign to get him to resign."

He called the Pope a brilliant teacher but said government was not his strongest point. "He's got to know his theology but I think I prefer somebody who can lead the church and pull it togther a bit," he said.

Benedict was the first pope to step down voluntarily since 1294, and conservatives fear the precedent will open the church to other possible innovations at a time when it faces profound challenges.

In Rome - doing its best on Wednesday morning, bathed in pale winter sunshine - Benedict made a poignant farewell at his final general audience, threading his way in the popemobile through the thousands gathered in St Peter's Square for a scheduled audience. Pilgrims and wellwishers gave him an affectionate farewell, waving placards saying "goodbye and thanks".

But only those already scheduled to attend the audience were allowed in the square, leaving many thousands more pressed up against the barriers and down the street, leaving Benedict the same remote figure he often seemed during his papacy.

For those in the audience, it was a bonus to be part of history - academics from Birmingham, England, and students from Birmingham, Alabama, plus students from Stubenville, Ohio, a Japanese women's college, and former Anglicans from England.

There were plenty of prelates present, whose minds must have turned partly to the coming few weeks and a conclave lacking any strong favourites. Cardinal Pell said he was unlikely to be promoted, but did not rule it out. "It could happen - I'm Catholic, I'm a bishop, I'm a cardinal," he said.

But this final public appearance by the introverted Mozart-playing cat-lover was a chance to focus on the present and the past. Benedict has not commanded anything lik te popular appeal of his predecessor, John Paul II, but Catholics have responded to an endearing shy humility that has marked him amid his travails. He concluded with Our Father in Latin and a gently voiced blessing.