|Polls have indicated widespread dissatisfaction in Britain with the way Benedict has handled the sex abuse crisis [AFP]
Pope Benedict XVI has said he is deeply ashamed of the "unspeakable" sexual abuse of children by priests in the Catholic Church.
During a mass at Westminster Cathedral in London on Saturday, he told British worshippers that he hoped the church's humiliation would help victims heal.
Benedict also said he hoped that the church would be able to use its contrition to purify itself from the "sins" of its ministers and be able to renew its commitment to educating the young.
He confronted the abuse scandal head-on during his homily, a day after six people were arrested in an alleged plot against him. They remained in custody on Saturday while police investigated the allegations against them.
He issued his latest comments amid speculation that he might meet British abuse victims.
"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," Benedict said.
He said he acknowledged the shame and humiliation all the faithful had suffered as a result of the sins, and said he hoped "this chastisement will contribute to the healing of the victims, the purification of the church and the renewal of her age-old commitment to the education and care of young people".
Benedict also met five victims of abuse for just over about 40 minutes, at the Vatican's ambassador's residence in Wimbledon, southwest London.
The Vatican said that he expressed to the four women and one man "deep sorrow and shame over what [they] and their families suffered".
The sex abuse scandal has clouded Benedict's four-day state visit to the United Kingdom.
Polls have indicated widespread dissatisfaction with the way Benedict has handled the crisis, with Catholics nearly as critical of him as the rest of the UK population.
Abuse victims and others opposed to his visit marched on Saturday afternoon to demand more accountability, before Benedict held a prayer vigil in Hyde Park.
On his way to Britain, he acknowledged that the church had failed to act quickly or decisively enough to stop the abuse and prevent it from happening again.
Victims groups have dismissed such comments as hollow, saying they want the church to turn over information it has about suspected paedophiles in its ranks.
Al Jazeera's Jonah Hull, at the protest near Hyde Park, said: "Thousands of people turned out to welcome the Pope but there is very strong sentiment against the visit as well."
About 10,000 protesters marched to the prime minister's residence at Downing Street, against Benedict's visit.
"He's apologised before. What they want is action and the Vatican to come clean on information which they say it has on child abuse by priests," Hull said.
Protesters also are opposing Benedict on issues of ordination of women priests, gay rights and the use of condoms.
He went ahead with a busy day on Saturday, his third in Britain, as the six men arrested over the alleged plot against him remained in police custody.
Police staged a pre-dawn raid on Friday on a garbage depot and arrested five street cleaners; a sixth person was arrested later in the day.
Police say they were detained under the Terrorism Act "on suspicion of the commission, preparation or instigation of acts of terrorism".
The Vatican has said Benedict was calm after being informed of the arrests and no changes to his itinerary were planned.
Al Jazeera's Barbara Serra, at the prayer vigil in Hyde Park, said: "Many things have overshadowed this trip ... But the atmosphere today here in Hyde Park for this prayer vigil is one of celebration.
"About 70 to 80,000 people are expected to come here of all different ages.
"This will be the biggest event he will have during his trip."