Pope Francis needs to set up a fund for nuns who quit religious life after abuse from priests and prelates, activists say, calling for greater attention on a long-neglected issue in the Catholic Church.

There are more than 600,000 nuns globally, and their exploitation and abuse has come to the fore in recent years, including in articles by the Vatican's official newspaper, L'Osservatore Romano.

Francis acknowledged the problem in 2019. Speaking of a specific women's religious order that was dissolved by his predecessor Benedict XVI in 2005, he talked of cases of "slavery" and "even sexual slavery".

German researcher and former nun Doris Reisinger, herself a victim of sexual and spiritual abuse by a priest, made the request during a press conference on Tuesday organised by abuse tracking group BishopAccountability.org.

"The pope has admitted abuse of nuns but he has not acted on it," she said. 

"And we have never heard a pope or bishop acknowledge coerced abortion at the hands of priests. They always treat abortion as a female issue yet they have never spoken about priests forcing abortions, despite knowing it is going on," she added.

The Vatican's press office did not immediately respond to a request for comment.

Church law should be changed to force orders of nuns to set aside money to help sisters who quit, Reisinger said. Until they do, the pope should create a central Church fund for this purpose, she added.

Reisinger urged Francis to also set up a fund for children fathered by priests, to save them from "a life of poverty and shame", and decree the mandatory defrocking of priests who force abortions on women they impregnate.

She said that nuns who take their vows as teenagers and renounce them as adults typically return to laicised life with no professional training, after years or decades cut off from friends and family. 

"It's literally impossible to go out there on your own," she said.

Reisinger said it was hard to estimate how many nuns faced sex abuse. She cited a 1998 survey by Saint Louis University in the United States on more than 1,100 nuns, which found that 12.5% of them reported being victims of sexual exploitation.

Just under 5% experienced what the study called "genital sexual contact", including oral sex and sexual intercourse, while more than 6% reported physical harassment such as kissing and inappropriate touching.