Pope Francis has for the first time admitted the Catholic Church has an ongoing problem with priests and even bishops who sexually abuse nuns, saying that more must be done to prevent it.

Speaking to reporters aboard the papal plane as he returned to the Vatican after a visit to the United Arab Emirates, he said some of the nuns had been used as sex slaves.

“It is true ... there have been priests and even bishops who have done this. I think it is still going on because something does not stop just because you have become aware of it,” he said, according to the Associated Press.

“We have been working on this for a long time. We have suspended some priests because of this.”

The Pope made the comments in response to questions about an article that appeared last week in a Vatican monthly magazine about the abuse of nuns in the church.

Pope Francis visits Ireland – in pictures Show all 55 1 /55 Pope Francis visits Ireland – in pictures Pope Francis visits Ireland – in pictures Pope Francis celebrates the Holy Mass at the Phoenix Park, in Dublin AP Pope Francis visits Ireland – in pictures Pope Francis arrives at Phoenix Park for a Papal Mass of the World Meeting of Families in Dublin EPA Pope Francis visits Ireland – in pictures A vigil takes place at the site of the mass grave which contained the remains of 796 named babies from the Bon Secours Mother and Baby home in Tuam. The vigil coincides with the Phoenix park mass which is taking place in Dublin held by Pope Francis. Excavations at the site in 2017 revealed underground structures which held babies bodies with ages ranging from 35 weeks to three years old with most of the dead buried in the 1950s when the facility was run by the Bon Secours Sisters, a Catholic religious order of nuns who received unmarried pregnant women to give birth Getty Pope Francis visits Ireland – in pictures An aerial view of the crowd at Phoenix Park Getty Images Pope Francis visits Ireland – in pictures Children queue for communion during Pope Francis' closing Mass PA Pope Francis visits Ireland – in pictures The Stand4Truth rally gathers outside a former Magdalene laundry in Dublin as part of the demonstrations against clerical sex abuse PA Pope Francis visits Ireland – in pictures Pope Francis leads the Holy Mass at Phoenix Park AFP/Getty Pope Francis visits Ireland – in pictures Pope Francis arrives to celebrate the Holy Mass at the Phoenix Park AP Pope Francis visits Ireland – in pictures The names of the victims are read out as a vigil takes place at the site of the mass grave which contained the remains of 796 named babies from the Bon Secours Mother and Baby home Getty Images Pope Francis visits Ireland – in pictures Pope Francis leads the Holy Mass at Phoenix Park AFP/Getty Pope Francis visits Ireland – in pictures A member of the clergy carries a bowl of incense PA Pope Francis visits Ireland – in pictures Pope Francis celebrates the Holy Mass at the Phoenix Park, in Dublin, Ireland, Sunday, Aug. 26, 2018. Pope Francis is on the second of his two-day visit to Ireland. (AP Photo/Matt Dunham) Matt Dunham AP Pope Francis visits Ireland – in pictures A vigil takes place at the site of the mass grave which contained the remains of 796 named babies Getty Images Pope Francis visits Ireland – in pictures Members of the public pray as they watch Pope Francis deliver a Papal Mass of the World Meeting of Families at Phoenix Park EPA Pope Francis visits Ireland – in pictures Pope Francis attends the closing Mass at the World Meeting of Families at Phoenix Park in Dublin PA Pope Francis visits Ireland – in pictures Pope Francis passes by a banner of a protester as he leaves St Mary's Pro-Cathedral AP Pope Francis visits Ireland – in pictures Pope Francis speaks during his visit to the Capuchin Day Centre for Homeless in Dublin AP Pope Francis visits Ireland – in pictures Pope Francis waves to the waiting crowds on Christchurch PA Pope Francis visits Ireland – in pictures Pope Francis waves to the waiting crowds on College Green PA Pope Francis visits Ireland – in pictures Members of the public wave at Pope Francis as he travels through the city Getty Images Pope Francis visits Ireland – in pictures Pope Francis laughs as he leaves St Mary's Pro Cathedral during his visit to Dublin Reuters Pope Francis visits Ireland – in pictures Two boys wave flags after climbing a post as they wait for Pope Francis Getty Pope Francis visits Ireland – in pictures Pairs of baby shoes are hung from black ribbons on Gardiner Street in Dublin in memory of the children who died at the Bon Secours Mother and Baby Home in Tuam, Co Galway PA Pope Francis visits Ireland – in pictures Crowds on O'Connell Street PA Pope Francis visits Ireland – in pictures DUBLIN, IRELAND - AUGUST 25: (NO SALES) In this handout image provided by Maxwell Photography for 2018 WMOF2018, Pope Francis and Taoiseach Leo Varadkar greet a child at Dublin Castle on August 25, 2018 in Dublin, Ireland. Pope Francis is the 266th Catholic Pope and current sovereign of the Vatican. His visit, the first by a Pope since John Paul II's in 1979, is expected to attract hundreds of thousands of Catholics to a series of events in Dublin and Knock. During his visit he will have private meetings with victims of sexual abuse by Catholic clergy. (Photo by WMOF2018/Maxwell Photography via Getty Images) Handout WMOF2018/Maxwell Photography/Getty Pope Francis visits Ireland – in pictures Pope Francis memorabilia on sale on O'Connell Street PA Pope Francis visits Ireland – in pictures Pope Francis arrives at St Mary's Pro-Cathedral during his visit to Ireland to attend the 2018 World Meeting of Families AFP/Getty Pope Francis visits Ireland – in pictures Pope Francis waves to the waiting crowds on O'Connell Street PA Pope Francis visits Ireland – in pictures Pope Francis addresses the congragation at St Mary's Pro-Cathedral AFP/Getty Pope Francis visits Ireland – in pictures Stephen O'Brien selling bottles of holy water from the St Mary's Pro Cathedral PA Pope Francis visits Ireland – in pictures Pope Francis prays inside St Mary's Pro Cathedral Reuters Pope Francis visits Ireland – in pictures A man waves a rainbow flag behind a model of a pope which stands in the window above a bar Getty Pope Francis visits Ireland – in pictures People hold a banner against Pope Francis on the way to St Mary's Pro-Cathedral AP Pope Francis visits Ireland – in pictures Nuns wait by the side of the road for Pope Francis Reuters Pope Francis visits Ireland – in pictures A model of a pope is placed in the window above a bar as crowds wait for Pope Francis to travel through the city Getty Pope Francis visits Ireland – in pictures Crowds on O'Connell Street, Dublin waiting to see Pope Francis as he travels in the Popemobile PA Pope Francis visits Ireland – in pictures Pope Francis waves to wellwishers as he arrives at Dublin Airport Getty Pope Francis visits Ireland – in pictures His visit, the first by a Pope since John Paul II's in 1979 is expected to attract hundreds of thousands of Catholics to a series of events in Dublin and Knock PA Pope Francis visits Ireland – in pictures Pope Francis talks to journalists aboard a plane flying from Fiumicino aiport to Dublin AFP/Getty Pope Francis visits Ireland – in pictures LGBT protestors from Dublin Pride and We Are Church with flags and umbrellas on Ha'Penny Bridge, Dublin to remember the victims of clerical sex abuse ahead of the start of the visit to Ireland by Pope Francis PA Pope Francis visits Ireland – in pictures Pope Francis disembarks from the aircraft as he arrives at Dublin Airport Getty Pope Francis visits Ireland – in pictures Woman wait for Pope Francis to drive past, in Dublin Reuters Pope Francis visits Ireland – in pictures Pope Francis arrives at Dublin International Airport, at the start of his two-day visit to Ireland, August 25, 2018. REUTERS/Clodagh Kilcoyne CLODAGH KILCOYNE Reuters Pope Francis visits Ireland – in pictures Taoiseach Leo Varadkar delivers a speech watched by Pope Francis in St. Patrick's Hall at Dublin Castle WMOF2018/Maxwell Photography/Getty Pope Francis visits Ireland – in pictures Protesters hold banners during a demonstration against clerical sex abuse, in Dublin Reuters Pope Francis visits Ireland – in pictures Pope Francis plants a tree during a meeting with Irish President Michael D Higgins, at Aras an Uachtarain PA Pope Francis visits Ireland – in pictures Pope Francis walks with the President of Ireland Michael Higgins at Aras an Uachtarain WMOF2018/Maxwell Photography/Getty Pope Francis visits Ireland – in pictures Pope Francis arrives at Dublin International Airport, at the start of his two-day visit to Ireland, August 25, 2018. REUTERS/Clodagh Kilcoyne CLODAGH KILCOYNE Reuters Pope Francis visits Ireland – in pictures Pope Francis, center, is flanked by Irish Prime Minister Leo Varadkar, right, as they arrive to meet authorities, in Dublin AP Pope Francis visits Ireland – in pictures Protestors wearing baby shoes, to signify the children who died in mother and baby homes in Ireland, protest in Dublin ahead of the start of the visit to Ireland by Pope Franci PA Pope Francis visits Ireland – in pictures Pope Francis exchanges gifts with Irish Prime Minister Leo Varadkar AFP/Getty Pope Francis visits Ireland – in pictures Pope Francis speaks with President Michael D Higgins in his study during a visit to Aras an Uachtarain in Phoenix Park, Dublin PA Pope Francis visits Ireland – in pictures Navy band march prior to the arrival of Pope Francis at the Presidential residence in Dublin AP Pope Francis visits Ireland – in pictures Eddie McGuinness from Dublin LGBTQ Pride carries a rainbow flag across Ha'Penny Bridge, Dublin ahead of the start of the visit to Ireland by Pope Francis PA Pope Francis visits Ireland – in pictures A message left by Pope Francis in the visitors book at Aras an Uachtarain in Phoenix Park PA

The magazine, Women Church World, revealed that some nuns were forced to abort the priests’ children or bear children that the priests refuse to recognise as their children.

“Should more be done? Yes,” the Pope said. “Do we have the will? Yes. But it is a path that we have already begun.”

The AP said in recent months, more and more nuns had been coming forward to report abuse, encouraged by the #MeToo movement, which drew strength from a flurry of revelations of assault and abuse against celebrities and senior figures in industry and the media in October 2017. Producer Harvey Weinstein, who has been charged with assault, has denied the allegations.

'I beg the Lord’s forgiveness' for child abuse 'betrayal' says Pope Francis at a service in Knock, Ireland

The news agency said that in 2018, the International Union of Superiors General, which represents more than 500,000 Catholic nuns, urged their members to report abuse.

The Pope said that former Pope Benedict dissolved a religious order of women shortly after his election as pontiff in 2005 “because slavery had become part of it (the religious order), even sexual slavery on the part of priests and the founder”.

He did not name the group, but Vatican spokesman Alessandro Gisotti said it was a French order.

Before he became pope, Benedict was Cardinal Joseph Ratzinger, the head of the Congregation of the Doctrine of the Faith, the Vatican department that investigates sexual abuse. The pope at the time was John Paul.

Then-cardinal Ratzinger wanted to investigate the religious order where women were being abused but he was blocked, Pope Francis said, without saying who prevented the probe.

Pope Francis has summoned key bishops from around the world to a summit later this month at the Vatican to find a unified response on how to protect children from sexual abuse by clergy.