The abortion pill mifepristone will remain temporarily available in the United States, but under tighter regulations, after a ruling by a federal appeals court late Wednesday.

A panel of three judges on the Fifth Circuit Court of Appeals in New Orleans, in the southern state of Louisiana, ruled 2-1 to keep mifepristone available.

Under the new order, access to the drug will also require three visits to physicians during the prescription period, and will be limited to women in the first seven weeks of pregnancy, down from 10.

Mifepristone was approved by the Food and Drug Administration (FDA) more than two decades ago and is used in more than half the abortions carried out annually in the United States.

However, Judge Matthew Kacsmaryk, an appointee of former Republican president Donald Trump, overturned the FDA's approval of the drug last Friday.

That ruling was paused for a week to allow an appeal, with Wednesday's judgment extending that pause beyond Friday as the FDA had requested.

The appellate court said its ruling would hold until the case was heard in full. Its tightened regulations roll back restrictions the FDA had eased in 2016.

The two circuit court judges who voted to tighten restrictions, Kurt Engelhardt and Andrew Oldham, were also both appointed by Trump.

The third, Catharina Haynes, is an appointee of former president George W. Bush.

The latest US standoff over women's reproductive freedom comes almost a year after the conservative-dominated Supreme Court overturned the landmark Roe v. Wade ruling that had enshrined the constitutional right to abortion for half a century.

US President Joe Biden on Tuesday branded Kacsmaryk's ruling as "out of bounds." His spokeswoman, Karine Jean-Pierre, told reporters during the president's visit to Dublin, Ireland on Thursday that the administration will continue fighting the ruling in court.

Jean-Pierre has previously described the ruling as "attack on FDA authority" and warned that it could "open the floodgates for other medications to be targeted and denied to people who need them."

Democrats and activists warn the ruling is part of a broader effort by Republicans to achieve a nationwide abortion ban.

Shortly after Kacsmaryk's decision on Friday, a judge in Washington state ruled in a separate case that access to mifepristone must be preserved.

The dueling legal opinions, along with the appeals, mean the issue is almost certain to end up before the Supreme Court.

Polls repeatedly show a clear majority of Americans support continued access to safe abortion, but conservative groups have sought to limit what had previously been a right enshrined in law.