(Reuters) - Alabama's governor signed a bill on Wednesday to ban nearly all abortions in the state, even in cases of rape and incest, in the latest challenge by conservatives to the landmark U.S. Supreme Court decision establishing a woman's right to terminate her pregnancy.

U.S. abortion rights activists had already vowed to go to court to block enforcement of the Alabama measure, the strictest anti-abortion law yet enacted with the intention of provoking reconsideration of the 1973 Roe v. Wade ruling.