Pope Francis will open a month-long summit of global Catholic leaders on Wednesday but it is likely to defer any decision on divisive issues such as women's ordination and blessings for same-sex couples until next year.

Speaking to a crowd of around 39,000 in the King Baudouin Stadium in Brussels, the pontiff wrapped up a difficult visit to Belgium by saying, "There is no place for the covering up of abuse."

Pope Francis has doubled down on his traditional views on abortion and women during his in-flight press conference coming home from Belgium.

Pope Francis on Tuesday led a prayer service asking forgiveness for the failings of the Catholic Church, including treatment by clergy of women and survivors of sexual abuse, as Catholic leaders prepared to begin a month-long summit at the Vatican.