RU486 suppresses the body's production of progesterone
Italy's drug regulation agency has approved the use of the abortion pill RU486, also known as mifepristone, prompting protests from the Vatican.
The Italian Pharmaceuticals Agency (AIFA) ruled late on Thursday that the drug would not be sold in pharmacies and only be administered by doctors.
The pill could only be taken up to the seventh week of pregnancy, it said.
On Thursday, the Vatican said it would excommunicate doctors who prescribed the drug and patients who used it.
"First abortion was legalised to stop it being clandestine, but now doctors are washing their hands of it and transferring the burden of conscience to women," said Bishop Elio Sgreccia, vice-president of the Pontifical Academy for Life.
RU486 was first introduced in France two decades ago and is available in the United States and several other European countries.
It allows the patient to have a chemically induced abortion instead of a surgical procedure within the first seven weeks.
The pill suppresses the body's production of a hormone called progesterone, causing the uterine lining to thin and reject an implanted embryo. There have been some concerns over its side-effects, which include heavy bleeding and nausea.
Youth Minister Giorgia Meloni said there was no contradiction with Italian law, which permits surgical abortion on demand in the first 12 weeks of pregnancy and until the 24th week only if the foetus has a genetic deficiency or to preserve the mother's health.
"If a woman can't be convinced to avoid an abortion, we should accept a less invasive and painful method," she said, but added that she personally "would never have an abortion".
Correspondents say it is not clear how many doctors will prescribe RU486 since, according to the health ministry, 70% of Italian doctors are "conscientious objectors" who refuse to carry out abortions.