The retiring leader of the world's 1.2 billion Catholics can still be referred to as "His Holiness Benedict XVI" and will have the additional title of "Roman pontiff emeritus", Vatican spokesman Federico Lombardi said on Tuesday.

He will continue wearing the white cassock normally reserved for pontiffs after he resigns on Thursday -- the first leader of the Catholic Church to do so since the Middle Ages -- but without the doubled shoulder cape, Lombardi said.

The 85-year-old German pontiff stunned the world when he announced on February 11 that he would step down at the end of the month, citing his age and failing strength, following a troubled eight-year papacy dominated by scandals and Vatican intrigue.

Scandals over paedophile priests and cover-ups by their superiors have cast a dark shadow over his papacy, continuing into his final days, with activists calling for cardinals Sean Brady of Ireland and Roger Mahony of the United States to be barred from the conclave.

"It may seem desperate to make this call at this moment, but we really believe the children of the world would be made safer by the stroke of Benedict's pen," David Clohessy, director of the Survivors' Network of those Abused by Priests (SNAP) told a news conference Tuesday.

The Vatican meanwhile gave more details on the delicate transition from pope to ex-pontiff.

Lombardi said Benedict has chosen to swap his trademark red shoes for a brown pair given to him by artisans in Mexico during a trip last year, adding that he would also stop wearing the gold Fisherman's Ring used to seal papal documents.

Tradition dictates that the ring be destroyed and a new one cast for each pope, but whether that occurs will be up to Vatican number two Tarcisio Bertone, the camerlingo or chamberlain who will be "interim pope" until a successor to Benedict is found.

The Vatican spokesman also said that a series of meetings of cardinals to settle on a date for the start of the papal election conclave could start on Monday. Benedict holds a final general audience in St Peter's Square on Wednesday, the eve of his formal resignation.

At least 50,000 pilgrims are expected to attend his final public appearance on Wednesday, enough to fill the famous square to overflowing, and the pope will ride the trademark white "popemobile" through the throngs.

But there will be no traditional kissing of the pontiff's hand -- not for security reasons, but because of the sheer size of the expected crowd, Lombardi said. "He doesn't want to favour one or the other" of the pilgrims, he added.

On his last day Thursday the pope will greet cardinals gathering for the conclave and a few dignitaries including from Slovakia, San Marino, Andorra and Benedict's native Bavaria. At around 5:00 pm (1600 GMT), the pope will board a helicopter for the 15-minute ride to Castel Gandolfo, the traditional summer residence of popes.

Benedict's "last public act" will occur about a half-hour later when he waves to the crowd from a balcony of the palace, Lombardi said. He said no fanfare will mark the official end of Benedict's papacy at 8:00 pm.

Instead the moment will be marked with quiet poignancy, when liveried Swiss Guardsmen will formally end their mandate to protect the pope. "The symbolic moment will come when the gates (of the Castel Gondolfo residence) close at 8:00 pm and the Swiss Guard leave," Lombardi said.

At a later date, Benedict will return to the Vatican, where a disused convent is being fitted as his retirement home. The decision to retire behind Vatican walls within a stone's throw of the new pope has raised eyebrows.
But Vatican expert John Allen of the National Catholic Reporter told AFP: "I frankly think that left to his own devices he would prefer to be in Regensburg (his German hometown).

"Several cardinals have told me it will be a lot harder for people to get to him" at the famously cloistered Vatican.

Commenting on SNAP's demands, Allen told AFP they were "another confirmation of how enormously damning this scandal has been for the Church. Even at the most awesome moment in the life of the Church (the papal election), this scandal rears its ugly head."

Asked whether Benedict will be the first former pontiff to be called "pope emeritus", Lombardi laughed and said: "We don't know what Celestine V was called when he stepped down. We'll have to ask the historians."
The 13th-century monk was the only other pope in the 2,000-year-old Church's long line of rulers to step down voluntarily -- saying he could not tolerate the intrigues of the Church hierarchy.