Pope Francis is allowing all priests to absolve women of the "grave sin" of abortion, extending indefinitely special permission he had granted for the duration of the just-ended Holy Year of Mercy.

Francis wrote in the Apostolic Letter made public by the Vatican on Monday that "there is no sin that God's mercy cannot reach and wipe away when it finds a repentant heart seeking to be reconciled" with God.

But he also wrote: "I wish to restate as firmly as I can that abortion is a grave sin, since it puts an end to an innocent life."

Because the Roman Catholic Church holds abortion to be such a serious sin, it had long put the matter of granting forgiveness for it in the hands of a bishop, who could either hear the woman's confession himself or delegate that to a priest who was expert in such situations.

But in 2015, Francis had said he was allowing all rank-and-file priests to grant absolution for an abortion for the duration of the Holy Year, which ran from Dec. 8, 2015 through Nov. 20, 2016.

By now letting all priests absolve the sin of abortion on a permanent basis following the end of the Holy Year, Francis is further applying his vision of a merciful church to those women who, as he has written in the past, felt they had no choice but to make "this agonizing and painful decision."

"May every priest, therefore, be a guide, support and comfort to penitents on this journey of special reconciliation" for faithful who had abortions, Francis wrote.

He explained his rationale thusly: "Lest any obstacle arise between the request for reconciliation and God's forgiveness, I henceforth grant to all priests, in virtue of their ministry, the faculty to absolve those who have committed the sin of procured abortion.

"The provision I had made in this regard, limited to the duration of the Extraordinary Holy Year, is hereby extended, notwithstanding anything to the contrary."

How to form consciences on abortion figured in how bishops in the United States advised their flock during the recently ended U.S. presidential election campaign.

Some pastors urged their congregations to keep the sacredness in life in mind when deciding which candidate would get their vote. The "sacredness of life" phrase is widely seen as referring to abortion. U.S. President-elect Donald Trump voiced his opposition to abortion while campaigning, while his Democratic opponent, Hillary Clinton, supported women's right to have an abortion.