Pope Francis begs forgiveness for Church sex abuses
Pope Francis has begged forgiveness from the victims of sexual abuse by priests, at his first meeting with the victims since his election.
He condemned the Church's "complicity" in hiding the abuse and said it must "weep and make reparation" for the "grave crimes" committed by clerics.
He met the six victims, two each from Ireland, Britain and Germany, after a private morning Mass in the Vatican.
The Church has been criticised after a series of abuse scandals worldwide.
At a press conference on Monday, Vatican spokesman Federico Lombardi said Pope Francis had spent half an hour with each of the victims who visited him. He said the Pope had also greeted the group at a dinner on Sunday evening.
The Pope said the abuses had been "camouflaged with a complicity that cannot be explained".
He apologised to victims for the "sins and grave crimes of clerical sexual abuse", which he described as "a sacrilegious cult" that insulted God.
He added: "I beg your forgiveness, too, for the sins of omission on the part of Church leaders who did not respond adequately [to reports of sex abuse]."
None of the six victims made public statements after their discussions with the Pope, the BBC's Alan Johnston in Rome reports.
Analysis: David Willey, BBC News, Rome
Pope Francis' heartfelt and humble apology on behalf of his church to six European victims of sexual abuse by Catholic clerics may go some way towards meeting criticism by victims' associations in many countries that he had failed to address adequately the scandal that predator priests have caused.
As usual, Pope Francis found original words to express his deep feelings of shame and sorrow. "Someone realised that Jesus was looking," he told the three men and three women invited to a private Mass in the Vatican guesthouse where he lives.
The Pope then spent the entire morning talking individually with them about the "life-long scars" left by what he compared to a "sacrilegious cult". Victims of clerical sexual abuse in Pope Francis' native Argentina have complained that none were invited to this unprecedented meeting, to which there was no media access.
Some victims' groups have criticised Pope Francis for having failed to meet their representatives sooner.
The Pope's predecessor, Pope Benedict, met abuse victims several times on trips outside Italy.
"It seems as though this is more of a public relations event for the Vatican and for Pope Francis," said Barbara Blaine, a member of an abuse survivors' group.
She said the Pope had not done enough to protect vulnerable children.
Former envoy convicted
Many survivors of abuse by priests are also angry at what they see as the Vatican's failure to punish senior officials who have been accused of covering up scandals.
Pope Francis last year strengthened the Vatican's laws against child abuse.
He has also set up a committee, whose members include a cardinal and an abuse victim, to draw up plans to tackle exploitation by priests.
The committee is expected to announce on Monday that it will expand to include more members from the developing world, Reuters news agency reports.
Last month, a Vatican tribunal convicted Josef Wesolowski, a former papal envoy to the Dominican Republic, of sex abuse and stripped him of the priesthood.
Wesolowski is the highest-ranking Vatican official to have been investigated over abuse claims.