Pope Francis's public admission that priests have used nuns as "sexual slaves", and may still be doing so, marks a new chapter in the abuse crisis rocking the Catholic church.

"It is the first time that the pope, but also the church as an institution, has publicly admitted this abuse is taking place, and that's hugely important," Lucetta Scaraffia, editor of the Vatican's women's magazine, told AFP yesterday.

The pontiff on Tuesday said Catholic priests and bishops had been sexually abusing nuns, and that his predecessor Benedict XVI had dissolved a religious order of women because of "sexual slavery on the part of priests and the founder." The Church has "suspended several clerics" and the Vatican has been "working [on the issue] for a long time," he said. The abuse was "still going on, because it's not something that just goes away like that. On the contrary," he added.

The nuns scandal broke as the Catholic church has had to contend with a wave of cases involving pedophile priests in countries worldwide from Ireland and the United States to Australia.

The papal admission followed a rare outcry last week from the Vatican's women's magazine, "Women Church World", over the rape of nuns, leaving them feeling forced to have abortions or raise children not recognized by their priest fathers.

"Many complaints have been filed with the Vatican and have not been followed up," said Scaraffia, who raised the issue in the February issue of "Women Church World", a supplement distributed with the Vatican's Osservatore Romano newspaper. "I very much hope that a commission will be set up to investigate, and that nuns expert in the issue will be called to take part," she told AFP.

Scaraffia said the clerical abuse of nuns was a global issue, but one particularly prevalent in Africa, Asia and Latin America. Reports of such abuse are known to have been made from Chile to the Democratic Republic of Congo, Italy, India, Kenya, Peru and the Ukraine.

Those abused "do not find it easy to speak out. They fear retaliation against them and their congregations," Scaraffia said. She said the issue was abusive power relationships, with clerics controlling everything from nuns' vocations to their salaries. "It's a very difficult situation which has its roots in the nuns' dependence within the church. They are not recognized as equals."