Pope Francis is encouraging Argentine women who are protesting a proposed new law to legalise abortion, saying the protection of life is above all a matter of human ethics.

In the letter to the women dated November 22, the Argentine pope wrote: "Is it fair to eliminate a human life to solve a problem? Is it fair to hire a hit man to solve a problem?"

After Francis's handwritten letter circulated on social media this week, the news portal of the Holy See confirmed Francis's intervention on Friday.

Vatican News said Francis was responding to a group of women from the shanty towns of Buenos Aires, where he used to minister, who have organised in recent years to oppose efforts to decriminalise abortion.

In the letter, Francis thanked the women for their activism and encouraged them, saying "the country is proud to have women like you".

President Alberto Fernandez announced earlier this month that he would present a bill to legalise abortion, saying it would save lives by preventing women from resorting to unsafe, clandestine procedures.

Francis's native country currently criminalises abortion except in the case of rape or risk to the mother's health.

Mr Fernandez campaigned on promises he would propose legislation to legalise it, but the coronavirus pandemic delayed movement on the proposal until this month.

Francis has strongly upheld Catholic doctrine forbidding abortion, denouncing it as part of today's "throwaway culture" that doesn't respect the dignity of the unborn, the weak or elderly.

He has, however, offered a merciful approach to women who have resorted to abortion, allowing mere priests and not just bishops to absolve them if they seek forgiveness.