Pope Benedict XVI is a card-carrying organ donor, it emerged today. The disclosure that the pontiff is prepared to donate organs for transplants after his death follows a front page article in the Vatican newspaper, L'Osservatore Romano, calling into question the concept of brain death as the end of life rather than cardio-circulatory arrest.

The article, by Lucetta Scaraffia, Professor Modern History at Rome University, set off a heated debate in Italy and was seen by some as an attack on organ transplants from the bodies of people declared to be brain dead. Professor Scaraffia appeared to admit this in an interview in which she said that she had "a certain resistance to organ transplants, I cannot accept them".

In response the Italian Association of Organ Donors confirmed that the Pope had signed up as a donor when he was a cardinal. In 1999, as Cardinal Joseph Ratzinger, he observed that organ donation was "an act of love", and said that he carried his membership card "with my personal details on it" at all times.

Kidneys, the heart, the liver, lungs, the pancreas and the small bowel can all be transplanted. In reality it is highly unlikely that any organs would be transplanted from Pope Benedict after his death, since the bodies of pontiffs are interred intact and revered. Until the death of John Paul II in 2005 they were embalmed.

Until the last century papal organs were removed — not for transplants but to make embalming more durable. The organs of 22 popes — from Sixtus V, who died in 1590, to Leo XIII, who died in 1903 — are preserved as relics in the church of Saints Anastasio and Vincent near the Trevi Fountain. The custom of removing the organs was abolished by Pope Pius X (1903-14).

Pope Benedict's support for transplants is seen as significant at a time when the Roman Church is debating the exact moments at which life begins and ends. It also has implications for traditional Catholic belief in bodily resurrection. In the 13th century the Fourth Lateran Council declared that "all men will rise again with their own bodies which they now bear about with them".

On the other hand the modern Catechism of the Catholic Church states that organ transplants "are in conformity with the moral law if the physical and psychological dangers and risks incurred by the donor are proportionate to the good sought for the recipient".

It adds: "Donation of organs after death is a noble and meritorious act and is to be encouraged as a manifestation of generous solidarity. It is not morally acceptable if the donor or those who legitimately speak for him have not given their explicit consent."

Professor Scaraffia noted that the Vatican had adopted brain death as the criterion for declaring a person dead after the publication of a landmark report by Harvard Medical School 40 years ago. However, members of the Catholic Church had voiced "many reservations", and in Vatican City itself "the certification of brain death is not used".

"The scientific justification of brain death rests on a peculiar definition of the nervous system that is now being questioned by new research, which casts doubt on the fact that brain death leads to the disintegration of the body," Professor Scaraffia said.

Professor Scaraffia, who is vice-president of the Italian Association for Science and Life and a member of the Italian National Committee on Bio-Ethics, noted that in 1991, as a cardinal, Pope Benedict had himself drawn attention to the danger that people who fell into an "irreversible coma" because of illness or an accident might have their organs used for transplants or experiments.

Professor Scaraffia said there had even been at least one case in which life support machines were used on a brain-dead pregnant woman to ensure that her blood kept circulating and her lungs continued to produce oxygen until the baby was delivered.

Such cases, she said, "have put into question the idea that these already were dead bodies, cadavers from which organs could be transplanted." Moreover the acceptance of the cessation of brain activity as death contradicted Catholic doctrine — which involved the "absolute and integral defence of human life" — by equating the human person with brain functions only.

Father Federico Lombardi, the Vatican spokesman, said that Professor Scaraffia's article was "interesting and authoritative", but did not reflect the position of the Holy See or signal any change in the Magisterium, the official teaching of the Church.

Cardinal Javier Lozano Barragan of Mexico, the Vatican "health minister" as head of the Pontifical Council for the Pastoral Care of Health Care Workers, said that Pope John Paul II had also accepted the concept of brain death, and had fully backed organ transplants. "Organ donation is a very good thing and the Church has always supported it," Cardinal Barragan said.

Corriere della Sera said that in Italy 9,682 patients were on a waiting list for organ transplants.