WASHINGTON - Pro-choice groups have warned that a law passed by legislators in the US state of North Dakota recognizing the "personhood" of a fetus would not only outlaw abortion but could also bar access to birth control.

Lawmakers in the North Dakota lower house voted 51 to 41 on Tuesday to pass the Personhood of Children Act, which confers the same basic rights on "all human beings from the beginning of their biological development, including the pre-born, partially born."

Pro-choice activist Lisa King holds a sign in front of the US Supreme Court on January 22, 2009 in Washington, DC. (AFP/Getty Images/File/Alex Wong) The bill is expected to go before the state senate in around two weeks.

If passed, it would be used to challenge the Supreme Court's 1973 Roe versus Wade decision that legalized abortion in the United States and gave the country some of the least restrictive abortion laws in the world, experts said.

Roe v Wade states that women in all 50 states have the absolute right to terminate a pregnancy during the first three months and a qualified right to do so up to six months.

By challenging Roe v Wade, pro-life activists aim to return the decision-making process on whether or not abortion is legal to the states, Brian Rooney of the Thomas More Law Center told AFP.

"The purpose of these laws is to challenge Roe v Wade. Once Roe v Wade is overturned, it doesn't mean abortion is illegal in all 50 states but it says that the states decide what to do with abortion," Rooney said.

In pressing for personhood laws to be passed by the states, pro-life advocates cite Supreme Court Justice Harry Blackmun, who drafted the Roe v Wade ruling, a morally and politically divisive issue in the United States since it was passed 36 years ago.

"Justice Blackmun said in the original Roe versus Wade decision that if personhood is ever established for the human being at the moment of his conception or creation, the Roe versus Wade decision would fall," Judie Brown, president of the pro-life American Life League said.

Republican state Representative Dan Ruby, who sponsored the North Dakota personhood act, said during the debate on the bill that its language was "what's required by Roe v Wade."

The 1973 Supreme Court decision "stipulated that before a challenge can be made, we have to identify when life begins, and that's what this does," he said.

But Tim Stanley, head of communications at the Planned Parenthood Federation of America branch representing North and South Dakota warned that the bill reached beyond a ban on abortion.

"The bill is written so broadly that it could easily impact other major life decisions in reproductive health care, including birth control and emergency contraception," said Stanley.

"It goes well beyond an abortion ban and well beyond what mainstream Americans and North Dakotans want," he told AFP.

Vicki Saporta, president of the National Abortion Federation, said: "While it is a direct challenge to Roe v Wade, we expect that the bill would not only ban abortion but could reach common forms of birth control as well."

Both pro-choice groups vowed to fight the bill, insisting it did not reflect the wishes of the US public.

"It's not a done-deal. We're hopeful we'll be able to make our case and stop this bill cold," Stanley said.

Saporta predicted the bill would be challenged in the courts if passed by the North Dakota senate and signed by the state governor.

And she said there was scant evidence that North Dakotans back the bill.

"There is no reason to believe that the population in North Dakota supports this legislation. If you look at South Dakota, where they tried twice to ban abortion in referenda, the voters of that state said 'no,'" Saporta said.

South Dakotans most recently rejected a proposed ban on abortion last year, the same year that voters in the state of Colorado roundly rejected a personhood law by three to one.

Surveys have shown that more Americans back a woman's right to choose whether or not to have an abortion than are pro-life, or against abortion.

But Brown, of the American Life League, hailed North Dakota for becoming the first state legislature to "act in a positive way" on a personhood law.

"As of today there are 19 states that have laws proposed, but no other state has got this far," she said.