WASHINGTON (AP) _ The Food and Drug Administration on Thursday approved U.S. use of the abortion pill RU-486, a major victory for those who battled for 12 years to bring the early-abortion method to this country.

Proponents say the pill, which has been used by millions of women in 13 countries, could transform abortion in the United States by making it more accessible and more private. But it can be used only in the earliest days of pregnancy.

Anti-abortion organizations have fought to keep RU-486 out of the United States since the drug debuted in France in 1988. They pledged to continue the fight.

To ensure the pill is used accurately and safely, the FDA mandated that women be given special brochures called ``MedGuides'' explaining who is eligible for a pill-caused abortion and what side effects to expect, and that they must make three trips to the doctor to undergo the procedure.

RU-486, now known by its chemical name mifepristone, can be used only within 49 days of the beginning of the woman's last menstrual period. The woman takes three mifepristone pills. Two days later, she returns to the doctor to swallow a second drug, misoprostol, that causes uterine contractions to expel the embryo. She returns for a follow-up visit within two weeks to make sure the abortion is complete.

The FDA will allow mifepristone to be distributed only to doctors trained to accurately diagnose the duration of pregnancy and to detect ectopic, or tubal, pregnancies, because those women cannot receive mifepristone.

Also, the FDA restricted mifepristone's use to doctors who can operate in case a surgical abortion is needed to finish the job or in cases of severe bleeding _ or to doctors who have made advance arrangements for a surgeon to provide such care to their patients.