Pope Francis has wrote to the bishops of the world to commemorate child victims of sexual abuse, urging religious community leaders to condemn all forms of oppression and exploitation of children.

The text of the letter, written on 28 December for the Feast of the Holy Innocents, was made public by the Vatican on 2 January. In it, His Holiness asks the bishops to be "more sensitive to what is happening" around them and to be attentive to the plight of children who face forced migration, illegal slave labour, prostitution and exploitation.

Pope Francis addressed specifically the paedophilia scandal that engulfed the Catholic Church in the 20th century. "It is a sin that shames us. Persons responsible for the protection of those children destroyed their dignity," the Pope admitted.

"We regret this deeply and we beg forgiveness. We join in the pain of the victims and weep for this sin. The sin of what happened, the sin of failing to help, the sin of covering up and denial, the sin of the abuse of power," he added.

The letter proclaims the Pope's commitment to ensuring that such atrocities would no longer take place within the Church. "Let us find the courage needed to take all necessary measures and to protect in every way the lives of our children, so that such crimes may never be repeated. In this area, let us adhere, clearly and faithfully, to 'zero tolerance'", he wrote.

Pope Francis first met with victims of child sex abuse at the hands of priests in July 2014. Victims groups said they needed more than meetings, they wanted the Pope to send a strong signal to priests around the world that sexual abuse would not be tolerated and that perpetrators would be reported to the local police authorities.