Pope Francis has asked forgiveness for Church leaders' "sins of omission" during a meeting with six people who were sexually abused by members of the priesthood.
The victims – from Ireland, Britain and Germany – met the pontiff at his residence and attended a private morning mass in the Vatican on Monday.
During the homily, the pope begged "forgiveness for the sins of omission on the part of Church leaders who did not respond adequately to reports of abuse made by family members, as well as by abuse victims themselves.
"This led to even greater suffering on the part of those who were abused and it endangered other minors who were at risk."
Pope Francis said that sexual abuse has a "toxic effect" on faith and hope as victims might feel betrayed and abandoned by God, which leads to a weakening of faith.
He then said that the presence of the six victims at the Vatican is a "miracle of hope, which prevails against the deepest darkness.
"Surely it is a sign of God's mercy that today we have this opportunity to encounter one another, to adore God, to look in one another's eyes and seek the grace of reconciliation.
"I express my sorrow for the sins and grave crimes of clerical sexual abuse committed against you. And I humbly ask forgiveness. The courage that you and others have shown by speaking up, by telling the truth, was a service of love."
The pontiff added that sexual abuse victims often commit suicide or seek relief in addictions, while others encounter difficulties in significant relationships.
"Suffering in families has been especially grave, since the damage provoked by abuse affects these vital family relationships," Francis said.
Francis concluded saying that there is no place in the Church for those who commit abuses and he committed himself "not to tolerate harm done to a minor by any individual, whether a cleric or not."
Pope Francis has been criticised for not having met with sexual abuse victims sooner.
Last December, the pontiff set up a Vatican taskforce to help tackle sexual abuse and paedophilia in the Catholic Church.
However, some argued the Vatican has not done enough to protect children from abuses.