Pope Francis
© Getty ImagesPope Francis cited the "scourge" of sexual abuse and said it was the responsibility of church leaders to "confront this evil afflicting the Church and humanity."
Pope Francis urged high-ranking church officials from around the globe gathered Thursday at the Vatican to "hear the cry of the little ones" who are victims of sexual abuse by priests.

Francis spoke at the beginning of a crucial, four-day summit that brought together almost 200 high-ranking church officials, including leaders of bishop conferences from more than 100 nations. The summit will focus on making bishops aware of their responsibilities regarding sexual abuse, as well as accountability and transparency, the Vatican said.

The pope cited the "scourge" of sexual abuse and said it was the responsibility of church leaders to "confront this evil afflicting the Church and humanity."

"The holy people of God look to us and expect from us not simple and predictable condemnations but concrete and effective measures to be undertaken," he said. "We need to be concrete."

Last week, Francis defrocked former U.S. cardinal Theodore McCarrick, 88, after Vatican officials found him guilty of sex crimes against minors and adults. McCarrick is the most senior Catholic official to be defrocked for such crimes.

Experts said McCarrick's case sends an important signal that even cardinals and powerful archbishops will be held accountable.

More than 30 years after the scandal first erupted in Ireland and Australia and 20 years after it hit the U.S., bishops and Catholic officials in many parts of Europe, Latin America, Africa and Asia still either deny that clergy sex abuse exists in their regions or downplay the problem.

Francis, the first Latin American pope, called the summit after drawing stiff criticism for his handling of a wide-ranging sex abuse cover-up case in Chile last year. He has vowed to demand accountability from church leadership.

Tuesday, two groups representing the leadership of Catholic religious orders apologized for their failure to quickly act to halt sexual abuse.

"We bow our heads in shame at the realization that such abuse has taken place in our congregations and orders, and in our church," said the statement from the Union of Superiors General and its female counterpart, the International Union of Superiors General.

Abuse survivors have also come to Rome to demand accountability, and the organizers of the summit met with some of them Wednesday.

Phil Saviano, who helped expose the U.S. abuse scandal by priests two decades ago, demanded that the Vatican release the names of abusers and their files.

"Do it to break the code of silence," he told the organizing committee on the eve of the summit. "Do it out of respect for the victims of these men, and do it to help prevent these creeps from abusing any more children."