Pope Benedict XVI broke his recent silence on the clerical abuse scandal Thursday, complaining that the church was under attack but saying that "we Christians" must repent for sins and recognize mistakes.

The main U.S. victims group immediately dismissed his comments, saying they are meaningless unless Benedict takes concrete steps to safeguard children from pedophile priests.

Benedict made the remarks during an off-the-cuff homily at a Mass inside the Vatican for members of the Pontifical Biblical Commission.

"I must say, we Christians, even in recent times, have often avoided the word 'repent', which seemed too tough. But now under attack from the world, which has been telling us about our sins ... we realize that it's necessary to repent, in other words, recognize what is wrong in our lives," Benedict said.

"Open ourselves to forgiveness ... and let ourselves be transformed. The pain of repentance, which is a purification and transformation, is a grace because it is renewal and the work of divine mercy," he said.

Victims of clerical abuse have long demanded that Benedict take more personal responsibility for clerical abuse, charging that the Vatican orchestrated a culture of cover-up and secrecy that allowed priests to rape and molest children unchecked for decades.

Those demands have intensified in recent weeks as the Vatican and Benedict himself have been accused of negligence in handling some cases in Europe and the United States.

"Factual disclosures are not 'attacks' and 'penance' protects no one," said Mark Serrano, a spokesman for the Survivors Network of those Abused by Priests, the U.S. group.

"When the Pope can't bring himself to utter the words 'pedophile priest' or 'child sex crimes' or 'cover-ups' or 'complicit bishops,' it's hard to have faith that he is able to honestly and effectively deal with this growing crisis," Serrano said in a statement.

Benedict's comments were his fullest allusion yet to the scandal since he sent a letter to the Irish faithful March 20 concerning what Irish-government inquiries have concluded was decades of abuse and church-mandated cover-up in the country.

In his letter, Benedict chastised Irish bishops for failures in leadership and judgment. But he took no responsibility himself or for the Vatican, which many victims have blamed for being more concerned about protecting the church than children.

Vatican spokesman the Rev. Federico Lombardi confirmed that Benedict was referring to the scandal with his comments Thursday. Summaries of the pontiff's remarks were reported on the front page of the Vatican newspaper L'Osservatore Romano and on Vatican Radio.

On Monday, the Vatican posted on its Web site what it claimed had been a long-standing church policy telling bishops that they should report abuse crimes to police, where civil laws require it.

But critics have said the guidelines were merely a deceptive attempt by Rome to rewrite history, designed to shield the Vatican from blame by shifting responsibility of dealing with abusive priests onto bishops.

The Rev. Thomas P. Doyle, a canon lawyer who has been the main expert witness for victims in hundreds of lawsuits, called the guidelines a "failed attempt at damage control through revision of history."

He noted that senior Vatican officials, including the current Vatican No. 2, Cardinal Tarcisio Bertone, were quoted in 2002 as saying the church shouldn't require bishops to report abusive priests to police because it would violate the trust the two shared.

"In practice, the policy has been to avoid contact with civil authorities and to cover up the crimes and the criminals," Doyle wrote in an article this week. "The newly created canonical tradition of referral to civil authorities is the result of one thing: public outrage, the exposure from the media and the pressure for accountability in civil courts."