CHICAGO (AFP) - The largely rural, but newly oil-rich, US state of North Dakota on Tuesday outlawed most abortions in a move to challenge federal laws protecting a woman's right to terminate a pregnancy.

The move came shortly after state legislators passed a law that asks voters to amend the state Constitution to define life as beginning at conception. If ratified in a November 2014 election, the amendment will grant full legal protection to embryos and foetuses and outlaw some forms of birth control, stem cell research and possibly in vitro fertilisation.

In the meantime, a Bill signed into law on Tuesday will ban any abortion after a foetal heart beat can be detected, typically around six weeks after conception when many women still do not realise they are pregnant. There are no exceptions for rape, incest, the health of the mother or if she loses the pregnancy anyhow as a result of a foetal abnormality.

Other Bills ban abortion as a result of genetic defects or for the purpose of gender selection and will require doctors at the state's only abortion clinic to have admitting privileges at a nearby hospital.

The laws will undoubtedly prompt legal challenges, but their supporters will welcome any chance this gives them to overturn the landmark Supreme Court "Roe versus Wade" decision that legalised abortion in 1973.

Republican Governor Jack Dalrymple ordered the legislature to allocate funds to fight any legal challenges and expressed hope he may prevail with the foetal heartbeat Bill.

"Although the likelihood of this measure surviving a court challenge remains in question, this bill is nevertheless a legitimate attempt by a state legislature to discover the boundaries of Roe v. Wade," he said in a statement.

"Because the US Supreme Court has allowed state restrictions on the performing of abortions and because the Supreme Court has never considered this precise restriction... the constitutionality of this measure is an open question."