Francis was speaking in Lisbon at the start of a five-day visit to the country in which he hopes to energise young Catholics during World Youth Day, the world’s largest Catholic festival.

The event comes less than six months after a report by a Portuguese commission said at least 4815 minors were sexually abused by clergy – mostly priests – over seven decades.

The crisis “calls us to a humble and ongoing purification, starting with the anguished cry of the victims, who must always be accepted and listened to,” Francis said in an address to bishops, priests and religious sisters at an evening vespers service in a monastery.

He spoke of today’s “growing detachment from the practice of the faith”, saying it had been accentuated by widespread disappointment and anger over the global abuse crisis and other scandals.

Francis is expected to meet privately with abuse victims before his trip ends on Sunday but details of the meeting have not been released.

The Pope landed in Lisbon to a sea of young Catholics who have poured into the city from around the globe for the World Youth Day festival, held every two or three years in a different city.

It is the fourth such event Francis will preside over since he became the pontiff.

In Lisbon, young believers jumped and sang as they proudly waved their country’s flag outside the Vatican embassy, where the Pope is residing.

Young Catholics from nearly every country in the world have registered for the event.

World Youth Day “is a sign of faith and union in which all of us get together for a cause”, 20-year-old Carlos Hernandez said.

“It’s very emotional.”

Francis has enacted numerous changes in the Church since his election in 2013 and has been pushing on with a series of reforms he hopes could leave a lasting legacy.

But he faces a delicate balance between appealing to more liberal believers and upsetting conservatives by giving women more roles and making the church more welcoming and less judgemental towards some groups, including the LGBT community.

At the opening Mass on Tuesday before the Pope arrived, Australian Andrew De Santos, 35, expressed hope the next generation would be able to move on from “errors” of the past.

Three huge billboards raising awareness of clerical sexual abuse were put up overnight in Lisbon hours before Francis’ arrival.

One was later removed.

On the plane to Portugal for the youth event, Francis vowed to “continue to stir things up,” a reference to his call during an earlier World Youth Day in Brazil to not be complacent but to make noise and instil change.

The 86-year-old Pope, who is making his first trip since intestinal surgery in June and uses a wheelchair and cane, appeared in good form and said he hoped to return to Rome on Sunday “rejuvenated by his encounter with young people”.

In his first speech of the trip, to President Marcelo Rebelo de Sousa and diplomats at a cultural centre, Francis said the world was currently “sailing amid storms on the ocean of history,” including the tempest of the war in Ukraine, and urged Europe to find the resolve to help end it and other conflicts.

He said Europe should divert money spent on armaments and use it to boost education and fund family-friendly legislation to help reverse a falling birth rate aggravated by prohibitive costs of housing for young couples.

He also urged Europe to rise to the challenge of “welcoming, protecting, promoting and integrating” migrants, both for humanitarian reasons and as a means of boosting dwindling populations.

-AAP