WASHINGTON, United States - The manufacturer of a widely used abortion pill asked the US Supreme Court on Friday to toss out a lower court ruling that would restrict access to the drug.

A US federal appeals court imposed restrictions last month on mifepristone but the ruling was put on hold pending an appeal to the Supreme Court.

Danco Laboratories, which markets mifepristone under the brand name Mifeprex, formally asked the nation's highest court on Friday to take up the case.

The Justice Department is expected to file a brief supporting Danco's request for the Supreme Court to review the ruling by the lower court.

Last month's ruling by a three-judge panel of the New Orleans-based 5th Circuit Court of Appeals would limit the use of mifepristone to the first seven weeks of pregnancy, instead of the current 10, and block it from being distributed by mail.

It would also require the abortion pill, which accounts for more than half of the abortions in the United States, to be prescribed by a doctor.

Anti-abortion groups are seeking to have mifepristone banned, claiming despite its long track record that it is unsafe. The case is the latest skirmish in the battle over reproductive rights in the United States.

The appeals court panel said the Food and Drug Administration (FDA), which approved the abortion pill in 2000 and made it more readily available in 2016, "failed to address several important concerns about whether the drug would be safe for the women who use it."

At a hearing in May, the judges pushed back against government arguments that the decision on whether to allow the use of mifepristone should be left to the FDA.

In its brief to the Supreme Court, Danco said the 5th Circuit ruling "upends FDA-approved conditions of use for Danco's drug Mifeprex.

"It does so at the request of a group of plaintiffs who do not prescribe or use the drug and whose real disagreement with FDA is that they oppose all forms of abortion," Danco said.

The case stems from an earlier ruling by a conservative US District Court judge in Texas that would have banned mifepristone.

The 5th Circuit blocked a ban on the abortion pill, but imposed the restrictions on access.

Conservatives wield a 6-3 majority on the Supreme Court, which overturned the constitutional right to abortion in a landmark ruling in June of last year.

Since then, some 20 states, mostly in the South and the Midwest, have prohibited abortion outright or restricted access while others, mainly on the coasts, have moved to protect it.

The FDA estimates that 5.6 million Americans have used mifepristone to terminate pregnancies since it was approved in 2000.