Abortion was thrust to the front of the US presidential campaign yesterday when the Food and Drug Administration (FDA) approved the sale of the abortion pill, RU-486, after a 12-year battle.

RU-486, which will be distributed in the US as Mifeprex, prevents a fertilised egg from attaching itself to the uterus, and can be used by women who are up to 49 days pregnant.

It was first marketed in Britain in 1991, but President George Bush banned its importation. That decision was reversed by the Clinton administration, and the FDA gave provisional approval for its manufacture in the US in 1996. When the original manufacturer pulled out in 1997 because of the controversy, the Population Council, a family planning organisation, persuaded Danco Laboratories to make the pill.

Anti-abortion activists who had tried to prevent the pill going on sale said they would now throw resources behind the Republican candidate, George W Bush, who opposes the pill's distribution.