Debate is growing on the merits of ordering priests to abstain from sex and marriage, which is designed to allow nothing interfere with their close relationship with God.

Some 6,000 parish priests who have left the priesthood to wed now live in Italy, compared to a total of 33,000 parish priests currently in service.

Pope Francis has previously supported the tradition of celibacy, but has suggested his position might waiver..

"For now, I am in favour of maintaining celibacy, with all the pros and cons that come with it, because in ten centuries there have been more positive experiences than errors," he was quoted saying in 2010, before he became Pope, in the book, On Heaven and Earth.

Pope Francis has revealed he had a girlfriend in Argentina as a young man before choosing to become a priest.

He has argued that celibacy is more Church tradition than hard and fast dogma, pointing out that up until 1100, some priests choose it while others did not.

And he suggested exceptions might be made, writing: "If, for the sake of argument, western Catholicism reviewed the celibacy question I think it would do so for cultural reasons (as in the East), not so much as a universal option." "It is a question of discipline, not faith. It can be changed." But he added: "Personally I never considered marrying."

In their letter, the women said they wished to come out in the open and support their partners "in their calling, which is strengthened by the vital force of love they discovered with us".

Turning to their own plight, the women wrote that "very little is known about the devastating suffering of a woman who is deeply in love with a priest".

The options priests in love faced were ending the relationship – often leaving both partners "scarred for life", leaving the Church, or carrying on in secret, the women wrote.

That, they said "involves living one's life in a constant state of hiding, frustrated by an incomplete love, with no hope of childbearing; a love that cannot see the light of day".

In one example supporting the anti-celibacy campaigners a prior at a Cistercian abbey near Milan has told how he was advised by his fellow monks to keep an affair he was having under wraps when he revealed he was in love with a woman.

"Do what you want, but keep it hidden," Father Alberto Stucchi said he was advised, according to the Italian newspaper La Stampa.

Father Stucchi decided to leave the order, before his new-found partner died of bone cancer.