The Pope today apologised for the “unspeakable crimes” committed by Catholic priests who sexually abused children.
In the most strongly worded public apology of his state visit to Britain so far, the Pontiff spoke of the “shame and humiliation” brought by the scandal.
He told the congregation at London’s Westminster Cathedral: “I think of the immense suffering caused by the abuse of children, especially within the Church and by her ministers.
“Above all, I express my deep sorrow to the innocent victims of these unspeakable crimes, along with my hope that the power of Christ’s grace, his sacrifice of reconciliation, will bring deep healing and peace to their lives.
“I also acknowledge with you the shame and humiliation which all of us have suffered because of these sins.”
The apology comes after he acknowledged this week that the Catholic Church had failed to deal with abusive priests decisively or quickly enough.
Today’s sermon was delivered in front of a congregation including former Prime Minister Tony Blair and his wife Cherie.
Earlier this morning the Pontiff was greeted by current Prime Minster David Cameron, the first time the two men have met since the Pope arrived in the UK.
The religious leader also spoke with other political figures including Britain's deputy prime minister Nick Clegg and acting opposition leader Harriet Harman.
Pope Benedict XVI’s address comes as six men remain in police custody after they were arrested over an alleged plot to attack him.
Five street cleaners were arrested yesterday morning as armed officers swooped on a depot as they prepared to start their shift. Hours later a sixth man was arrested at a home in north London.
Opening his sermon at the main Catholic church of England and Wales, the Pope thanked those present for their "warm reception".
He added: “I am especially happy that our meeting takes place in this Cathedral dedicated to the Most Precious Blood, which is the sign of God’s redemptive mercy poured out upon the world through the passion, death and resurrection of his Son, our Lord Jesus Christ.”
And he welcomed Dr Rowan Williams saying: “In a particular way I greet the Archbishop of Canterbury, who honours us by his presence.”
During the 13-minute address, Pope Benedict spoke of the “insights and teachings” of Cardinal John Henry Newman, the Victorian intellectual and preacher who will be beatified by the Pontiff tomorrow in Birmingham.
He said: “May the profound ideas of this great Englishman continue to inspire all Christ’s followers in this land to conform their every thought, word and action to Christ, and to work strenuously to defend those unchanging moral truths which, taken up, illuminated and confirmed by the Gospel, stand at the foundation of a truly humane, just and free society.
“How much contemporary society needs this witness! How much we need in the Church and in society, witnesses of the beauty of holiness, witnesses of the splendour of truth, witnesses of the joy and freedom born of a living relationship with Christ!”
And he said one of the “greatest challenges” facing Catholics today was how to “speak convincingly of the wisdom and liberating power of God’s word to a world which all too often sees the Gospel as a constriction of human freedom, instead of the truth which liberates our minds and enlightens our efforts to live wisely and well, both as individuals and as members of society.”
He added: “Let us pray, then, that the Catholics of this land will become ever more conscious of their dignity as a priestly people, called to consecrate the world to God through lives of faith and holiness.”
And he said: “The more the lay apostolate grows, the more urgently the need for priests is felt.”
Concluding his sermon, the Pontiff urged listeners “once more to look to Christ,” adding: “I pray that in doing so, you may join the ranks of faithful believers throughout the long Christian history of this land in building a society truly worthy of man, worthy of your nation’s highest traditions.”