Pope Francis urged bishops to confront and not conceal the sexual abuse of children during an open-air mass on Sunday, marking the end of his three-day visit to Belgium, a country still grappling with the aftermath of past scandals.

Around 40,000 faithful, some waving Belgian and Vatican flags, gathered in the bright morning sunshine at King Baudouin stadium north of the capital to hear the 87-year-old pontiff. "There is no place for abuse, there is no place for covering up abuse," Francis declared during his homily. "I ask everyone not to cover up abuse, I ask the bishops not to cover up abuse, to condemn the abusers and help them heal themselves of this disease of abuse."

During his visit, the pope was repeatedly questioned by Belgian authorities and victims' advocates about the Catholic Church's handling of child sexual abuse, a topic reignited by a powerful documentary last year. The documentary led around 200 more people to come forward with allegations of abuse by Church members, adding to the approximately 1,000 cases reported previously.

On Friday, Francis met with 17 victims. "I felt their suffering," he told the Sunday mass. "Evil must not be hidden, evil must be brought out into the open, let it be known," he added, urging for all perpetrators to be judged. In a sign of ongoing challenges, the program for Sunday's mass had to be altered at the last minute after it was discovered that the closing hymn was composed by a priest accused of sexual abuse. This oversight prompted Archbishop Luc Terlinden, head of the Belgian bishops' conference, to acknowledge the need for better monitoring of cases and perpetrators.

Despite the shadow cast by the abuse issue, the Argentine pontiff received an enthusiastic welcome at Sunday's mass, with young people and families cheering as he toured the venue in his Popemobile. "He transmits all kinds of values," said Olivier Caillet, 44, from Brussels, praising the pope's welcoming stance on migration. "He's a bit like the pope of surprises, he's with the underprivileged... he's opening up new possibilities, trying to change people's consciences so that we don't close borders like barriers."

Belgium's King Philippe and Queen Mathilde were also present at the mass, where Francis appealed for an immediate ceasefire in Lebanon and the wider Middle East. "I call on all parties to immediately cease fire in Lebanon, Gaza, the rest of Palestine and Israel," the pontiff said, as Israel continued to target the Hezbollah armed group in Lebanon.

Francis's visit, the first by a pope to Belgium since John Paul II in 1995, also highlighted the growing divide between the Vatican and some faithful in progressive, secular countries over issues such as gender inequality. On Saturday, he faced a candid discussion with students about the role of women in the Church, following a tribute to a former sovereign who publicly opposed abortion. His response, describing women as daughters, sisters, and mothers, upset some, leading the Catholic university hosting the meeting to express its "incomprehension and disapproval" at the reductive view.

"I don't understand why women can't become priests. It's something that was established because it was rooted in society at the time, but now we've moved on," said Alice Vanwijnsberghe, an 18-year-old student, after attending a festival with 6,000 young Catholics. The pope departed Brussels at around 1.30pm, taking off from the Melsbroek military airport outside the city, and was expected to hold his traditional press conference on board the aircraft taking him back to Rome.