Pope Francis has acknowledged that members of the Catholic clergy abused nuns, adding to a string of recent allegations about widespread sexual abuse by priests and coverups by the church hierarchy.

"It's not that everyone does this, but there have been priests and bishops who have," Francis told reporters aboard the papal plane on Tuesday, according to the Associated Press. The wire service and other outlets had reported on allegations of nun abuse over the past year, but the pontiff had not previously confirmed that such abuse took place.

Francis is due to host a gathering of bishops and cardinals in two weeks to address the broader global issue of clergy sexual abuse - including, largely for the first time, of adult victims and accountability for those at the top of the church who mismanage and cover it up.

The Post's Stefano Pitrelli and Chico Harlan wrote in September, when the meeting was announced, that the meeting "is believed to be unprecedented, indicating that the church recognizes that clergy sex abuse is a global problem - even in countries where the church maintains strong social power and cases have not come to light in great numbers."

"The Church's credibility has been seriously undercut and diminished by these sins and crimes, but even more by the efforts made to deny or conceal them," Francis wrote in a letter to U.S. bishops last month. "This has led to a growing sense of uncertainty, distrust and vulnerability among the faithful."

Asked whether he would take a similarly broad approach to tackling the abuse of nuns, Francis signaled that he would. "Should we do something more? Yes. Is there the will? Yes. But it's a path that we have already begun," he said, the AP reported.

Francis has been criticized in the past for his handling of the topic. In January 2018, he dismissed accusations that Chilean bishop Juan Barros had covered up sexual abuse committed by a priest named Fernando Karadima. "There is not one shred of proof against him. It's all calumny. Is that clear?" the pope said at the time. He later apologized and dispatched investigators to Chile but did not condemn Barros.

Some are also dissatisfied by what they consider a slow Vatican response to major sexual-abuse scandals that broke in other countries, including Australia and the United States.

"The church remains quiet about its investigations and disciplinary procedures," Harlan reported last year.

"It does not release any data on the inquiries it has carried out. A proposed tribunal for judging bishops accused of negligence or coverup was quashed by the Vatican department that was supposed to help implement it. And, rather than being fired and publicly admonished, offending church leaders are typically allowed to resign without explanation."

A few high-profile allegations against top Catholic clerics by nuns have gained attention in the last year, with some Catholics calling it a #MeToo moment for religious sisters.

Last fall, Indian nuns in the state of Kerala made news by marching with placards, demanding action against a bishop they say raped a nun between 2014 and 2016. After reportedly getting no response from the church to her complaint, she went to police in June - a radical move in the state.

"There are many nuns within the church who are suffering. They are afraid to come out. The church mechanism is a very large and powerful one," a lawyer who was helping the women, Indulekha Joseph, told the Washington Post last year. "The other problem is once a nun speaks, she is thrown out of the convent and may find herself on the street, because often her family is not willing to accommodate her. A campaign of character assassination starts. The nun will be portrayed as a prostitute."

Last month, a Vatican official who handles sexual abuse cases for the church quit after being accused of sexual abuse by a former nun. The woman, Doris Wagner, last year had accused an unnamed priest of making sexual advances on her while in confessional. She later identified the priest as Hermann Geissler, who was chief of staff of the Congregation for the Doctrine of the Faith, a body that handles discipline in sexual abuse cases within the Catholic Church.

Geissler has maintained his innocence but said he was resigning to protect the church.