Women's access to a widely used abortion pill in the US has been maintained by the Supreme Court during an ongoing legal battle over the drug.

The justices agreed to stay or pause a lower court decision imposing restrictions on the availability of mifepristone during a challenge by anti-abortion groups to its federal regulatory approval.

Mifepristone, which was licensed in 2000, is used in combination with a second drug, misoprostol, and accounts for more than half of all abortions in the US.

President Joe Biden hailed the high court for keeping the pill available while the court fight continues.

"As a result of the Supreme Court's stay, mifepristone remains available and approved for safe and effective use while we continue this fight in the courts," Mr Biden said in a statement.

"The stakes could not be higher for women across America. I will continue to fight politically-driven attacks on women's health.

"But let's be clear - the American people must continue to use their vote as their voice, and elect a Congress who will pass a law restoring the protections of Roe v Wade."

His administration is seeking to defend mifepristone in the face of mounting abortion bans and restrictions imposed by Republican-led states since the Supreme Court in June 2022 overturned the landmark 1973 Roe v Wade decision that had legalised the procedure nationwide.

Opponents argue the Federal Drug Agency (FDA) illegally approved mifepristone and then removed critical safeguards on what they describe as a dangerous drug.

Erik Baptist, a lawyer for the conservative religious rights group Alliance Defending Freedom said: "Our case seeking to put women's health above politics continues on an expedited basis in the lower courts."

Carol Tobias of National Right to Life said: "What the courts will see is a drug that does not cure a disease or alleviate the symptoms of a disease.

"It was developed to take the life of an unborn child and always has the potential to harm the mother."

The FDA has called mifepristone safe and effective, highlighted by decades of use by millions of people, with adverse effects exceedingly rare.

Mr Biden said: "I continue to stand by FDA's evidence-based approval of mifepristone, and my administration will continue to defend FDA's independent, expert authority to review, approve and regulate a wide range of prescription drugs."

Jessica Ellsworth, a lawyer for the pill manufacturer Danco Laboratories said the Supreme Court's decision "preserves crucial access to a drug relied on by millions of patients" after lower courts had caused "widespread chaos."

Abortion rights groups praised the Supreme Court's decision, but noted the case was ongoing.

The Supreme Court did not rule on the merits of the case meaning that mifepristone could still be restricted or banned at a later stage.

"We're not out of the woods yet," said Nancy Northup of the Centre for Reproductive Rights.

Joshua Sharfstein, a public health professor at Johns Hopkins University and a former FDA official said: "It's the right decision and a huge relief.

"The alternative would have not only undermined access to reproductive health care, it would have thrown into disarray drug regulation in the United States."