Sydney - Wellwishers are expected to flock Thursday to Sydney's majestic harbour for Pope Benedict XVI's grand entrance for a Catholic youth festival that has drawn over 200,000 pilgrims to Australia's biggest city.

The Holy Father arrived Sunday for the week-long World Youth Day celebrations but spent an early spell at a rural retreat outside the city before taking up lodgings beside a gothic cathedral in the city centre.

The obligatory meetings with Prime Minister Kevin Rudd and other dignitaries over, the 81-year-old will take to the water in a
14-boat flotilla that will sail past the Opera House and under the iconic Harbour Bridge.

Waiting for him at a former container terminal cleared specially for the pope's first visit to Australia are expected to be up to 225,000 registered pilgrims, more than half of them from abroad.

From more than 170 countries, they have braved the nip of the southern hemisphere winter and the discomfort of being billeted in school halls or the stadiums used for Sydney's 2000 Olympic Games.

Their mornings are taken up with bible study, leaving the rest of the day free for a conviviality that has surprised, even embarrassed, some jaded city folk by its unabashed glee.

"It's something about being around so many like-minded people," Sydney church worker Michelle Reynolds said when explaining the "mass hysteria" noted approvingly by a local newspaper. "Sometimes, to be young and Catholic you can feel really alone. If you say you go to mass every week, you can be looked at quite funny."

The pope will address pilgrims after disembarking from his "boat- a-cade." Likely topics include caring for the planet's ecosystem and standing firm against the march of secularism.

A quarter of Australia's 21 million people are Catholics, but regular attendance at mass is now down to 14 per cent of those Down Under who profess to be part of the pope's 1.1 billion global flock.

During his stay, which ends Monday, the Holy Father is expected to repeat an apology to victims of sexual abuse by the clergy that he gave during his April visit to the United States. It is likely to come Saturday.

The church has been dogged over the last decade by charges that it has done more for the perpetrators than their victims - a concern highlighted by an injudicious remark by World Youth Day organizer Bishop Anthony Fisher, when he said that the public should relish the joy of the pilgrims "rather than dwelling crankily, as a few people are doing, on old wounds."

Speaking before his meeting with the pope, the devoutly religious prime minister said that a papal apology to victims of sex abuse by priests was strictly a matter for the Catholic Church.

Rudd said the apology in the US had brought "great comfort and healing" but added that he would not "stand outside the church and provide them with public lectures in terms of how they should behave."

There was no gainsaying that the youngsters taking over the harbour city had brought it a vim and vigour without parallel in its history.

"It appears to be a like a party, an unusual atmosphere in Sydney," Vatican spokesman Father Federico Lombardi told reporters when vouchsafing the views of the pontiff.

An opening mass Tuesday at the former cargo wharf that drew more than 150,000 worshippers set the scene for celebrations that culminate Sunday with a mass that could draw up to 500,000 to a city racecourse. The pilgrims will trek to the venue over the course of Saturday, sleep under the stars and wake to the prospect of Sunday Mass given by the German-born pope. (dpa)