( dpa ) - Pope Benedict XVI on Thursday said the practice of in vitro fertilization - when human egg cells are fertilized by sperm outside a woman's womb - had "breached the barrier that safeguards human dignity."
The pontiff made the remark in a speech to members of the Congregation for the Doctrine of the Faith, the Vatican's watchdog on moral and religious teachings.
Benedict, referring to a 1987 document issued by the Congregation - which he headed at the time as Cardinal Joseph Ratzinger - said the church in its criticism of in vitro fertilization (IVF) had anticipated several subsequent bio-ethical problems.
The document, titled Donum Vitae (Gift of Life), holds that IVF is morally wrong because it replaces the "natural" sexual union between husband and wife.
It also condemns the practice because it often results in the destruction of some embryos - a violation of human life which the church identifies as such from conception.
IVF had ushered in new "connected "problems said Benedict, such as the freezing of human embryos and the practice of selecting or discarding them based on scientific tests, stem cell research and cloning.
"When human beings in the most vulnerable state of their existence are selected, abandoned, killed or treated as 'biological matter,' how can it be denied that they are being treated like 'something' rather than 'someone' and thus question the very concept of human dignity," the pontiff said.
Benedict said "the Church appreciates and encourages progress in the biomedical sciences, which opens up previously unimagined therapeutic possibilities."
But he added that it was also the church's duty "to enlighten everyone's consciences so that scientific progress may be truly respectful of all human beings."