The opinion, written by Republican-appointed judge, Justice Samuel Alito, was published by Politico in what is an unprecedented leak from the court.

The decision, which could still change, would leave it to individual states to determine the legality of abortion.

Four other Republican-appointed justices – Clarence Thomas, Neil Gorsuch, Brett Kavanaugh and Amy Coney Barrett – voted with Justice Alito in the conference held among the justices, according to Politico.

It reported that Justices Stephen Breyer, Sonia Sotomayor and Elena Kagan were working on dissenting opinions. It was not clear how Chief Justice John Roberts planned to vote.

About half of the states – mostly in the midwest and south – are expected to ban abortion.

The decision has been condemned by abortion rights supporters as an attack on women, with protestors gathering at the Supreme Court.

Nancy Northup, president of the Center for Reproductive Rights, said the move “would represent the most damaging setback to the rights of women in the history of our country”.

The New York Times described the leak as a “seismic breach of the court’s usually reliable confidentiality”.

Overturning Roe would reduce the number of legal abortions by about 14 per cent, according to research. Some states are also making provision to help women who live in states that ban the practice.

Those who cannot travel will be forced to order pills online, conduct dangerous procedures themselves or simply go through with the birth.