Pope Benedict XVI begged forgiveness Friday from victims of sexual abuse by priests, but advocates for the victims say they want action rather than more words from the Vatican.

"We're all sort of getting apology fatigue at this point, I mean this is the fourth or fifth time he's apologized," Peter Isley, of the U.S.-based Survivors Network of those Abused by Priests (SNAP), told CTV News Channel from Rome.

"Which is fine but our concern is that it's not concrete action. An apology is not an arrest."

The Pope also promised to "do everything possible" to ensure that no more Roman Catholic priests rape or molest children again, a pledge he has made in the past.

Friday's apology was issued during a Mass in St. Peter's Square, attended by 15,000 white-robed priests, marking the end of the Vatican's Year of the Priest.

In his homily, the Pope lamented that during what should have been a year of joy for the priesthood the "sins of priests came to light -- particularly the abuse of the little ones."

"We too insistently beg forgiveness from God and from the persons involved," the pontiff said, "while promising to do everything possible to ensure that such abuse will never occur again."

This past year has been marked by revelations of hundreds of new cases of sexual abuse by priests, coverups by church officials in several nations and Vatican inaction to root out the pedophiles in the ranks of the priesthood.

Isley said the Pope should have gone further in Friday's homily, including a vow to defrock any priest who has ever abused a child.

"He could've said it today; he should've said it today: That from now on, any priest who has sexually assaulted a child will not be a priest," Isley said. "There are children who are at risk right now, around the globe. There are pedophile priests in parishes, in ministries, that bishops and archbishops know about."

"That is much, much more important than an apology."

He also questioned the Pope's personal credibility in dealing with the issue, pointing to evidence suggesting that while he was a cardinal, Pope Benedict did nothing to remove a U.S. priest accused of molesting up to 200 deaf boys at a Milwaukee school.

Benedict's legacy has also been tarnished by his actions as archbishop of Munich in the 1980s, when he approved therapy for a suspected pedophile priest who was allowed to resume pastoral duties while being treated. The priest, the Rev. Peter Hullermann, was later convicted of molesting a boy.

"He has to personally explain his personal involvement in cases that are now emerging … of his direct involvement in covering up and concealing priest child sex molesters," Isley said. "Not doing that is going to make his credibility … very, very compromised."

The Pope said that the Church needs to do a better job of screening those it admits into the priesthood.

"We will do everything we can to weigh the authenticity of their vocation and make every effort to accompany priests along their journey, so that the Lord will protect them and watch over them in troubled situations and amid life's dangers."

His comments were similar to those reported from his private meeting with abuse victims in Malta in April, during which the pontiff had tears in his eyes as he heard the stories of men molested by priests as children.

Benedict said the scandal had shown the need for a purification of the church. "Had the Year for Priests been a glorification of our individual human performance, it would have been ruined by these events," he said. "But for us what happened was precisely the opposite: We grew in gratitude for God's gift."

A Spanish priest who attended Friday's Mass, the Rev. Davide Torrijus, concurred.

"We have all suffered during the year of the priests" because of the scandal, he said. "It was good for the pope to show also the positive aspects -- gratitude for the gift."

Isley however remained skeptical about promises of change.

He charged that the Vatican is currently holding an estimated 4,000 files on pedophile priest which should be in the hands of police and said the Pope should order their release.

"Order every bishop and archbishop to take the files of criminal evidence that they have in their archives, in their secret files that we now know about and turn those over to law enforcement," Isley said.

"Then we can move on to questions of forgiveness and repentance and all that kind of stuff."

With files from The Associated Press