The Food and Drug Administration (FDA) approved RU-486 (mifepristone) for the termination of early pregnancy, defined as 49 days or less, counting from the beginning of the last menstrual period. The administration said it based its approval of mifepristone on data about safety and effectiveness from clinical trials in the United States and France. It is estimated that more than half a million women in Europe have used mifepristone since its debut in France 12 years ago.

Supporters lauded the approval as a milestone, making abortion more private and improving access for women living in areas where surgical abortions are not available. Antiabortion organisations, which have fought since 1988 to keep RU-486 out of the United States, assert that the pill carries health risks for women. The FDA's announcement has prompted a flurry of statements from politicians and organisations on both sides of the issue.

Texas governor and Republican presidential candidate George W Bush called the decision wrong, saying: “I fear that making this abortion pill widespread will make abortions more and more common… As president, I will work to build a culture that respects life.”

Vice President and Democratic presidential candidate Al Gore agreed with the FDA. “Today's decision is not about politics,” he said, “but the health and safety of American women and a woman's fundamental right to choose.”

The National Right to Life Committee vowed to fight RU-486 through educational efforts. Spokeswoman Laura Echevarria said that the organisation would make sure “women know about the development of their unborn child, that about the time an RU-486 abortion takes place, an unborn child's heart has most likely begun to beat.”

Mifepristone works by causing the embryo to detach from the uterine lining. To induce an abortion, the drug is taken with misoprostol, which causes contractions and aids in expelling the embryo. Under the approved regimen, a woman first takes three mifepristone pills by mouth. Two days later, she returns to the doctor to take the second drug. She returns for a follow up visit within two weeks to make sure the abortion is complete.

Under the terms of the approval, mifepristone will be distributed to physicians who have access to ultrasonography to determine the duration of a patient's pregnancy and detect an ectopic pregnancy, which is a contraindication for use of RU-486. Physicians who prescribe mifepristone must also be able to provide surgical intervention in cases of incomplete abortion or severe bleeding, the FDA said, or they must have made plans in advance to provide such care through others. In about one of 100 women, bleeding can be so heavy that a surgical procedure will be required to stop it.

Advocates and opponents say the abortion pill's impact could be muted by trepidation among doctors about prescribing the controversial drug.