Campaigners criticise state's supreme court for refusing to block amendment that will appear on 8 November ballot

Mississippi voters will be allowed to vote on an initiative that seeks to reverse abortion rights by redefining the term "person" to apply at the moment of conception.

The state's supreme court refused to block the amendment, which will now appear on the general election ballot on 8 November. A majority of the justices said they could not rule on whether measures were constitutional until voters of the legislature had had a chance to pass them.

Civil rights campaigners criticised the court ruling and described the measure as "harmful to women".

Nsombi Lambright, executive director of the ACLU of Mississippi said: "We're disappointed with the ruling. A measure will be on the ballot that will allow the government to dictate what is a private matter that's best decided by a woman and her family, within the context of her faith. Mississippi voters should reject this intrusive and dangerous measure."

Bear Atwood, legal director of the ACLU of Mississippi, said: "This initiative is extreme and could severely undermine women's access to birth control, in vitro fertilization and life-saving medical procedures."

Measure 26 seeks to alter the term person or persons to include "every human being from the moment of fertilisation, cloning or functional equivalent thereof".

It is part of a swing across conservative states, particularly in the south, towards legislating for life to begin at conception, thus undermining piecemeal Roe V Wade, the landmark US supreme court ruling that set out the right to abortion.

The initiative was challenged by a Mississippi citizen because it failed to comply with the state's official ballot initiative process which forbids making modifications to the Bill of Rights.

Cristen Hemmins, the plaintiff, said: "As a lifelong Mississippian, I am disappointed that this broad and intrusive measure has been allowed on the ballot. I call on all voters to vote 'no' on #26. The government should not be interfering with the personal and private health care decisions of Mississippi families."

But anti-abortion groups such as the American Family Association and Pro-Life Mississippi welcomed the judge's decision.

"Today we rejoice and celebrate this hard-won victory, but tomorrow we roll up our sleeves and return to work," Stephen Crampton, the attorney for the proponents told the Associated Press. "Our opponents are discouraged, but not yet ultimately defeated. They will be back, spreading fear, confusion, and dire 'sky-is-falling' warnings about this simple Amendment, and we must be ready to rebut their baseless charges and set the record straight."

The ruling follows that three months ago, when Rennie Gibbs, of Mississippi, became the first woman to be charged with murder following the stillbirth of her baby. Across the US, more and more prosecutions are being brought that seek to turn pregnant women into criminals.