AUSTIN, TEXAS -- The U.S. Justice Department on Monday appealed a Texas court ruling that would halt approval of a drug used in the most common method of abortion in the U.S., calling the decision "extraordinary and unprecedented."

If allowed to stand, the order issued last week by U.S. District Judge Matthew Kacsmaryk could restrict access to the abortion medication mifepristone as early as Friday, unsettling abortion providers less than a year after the reversal of Roe v. Wade already dramatically curtailed abortion access.

The U.S. Food and Drug Administration in 2000 granted approval to mifepristone, one of two drugs used for medication abortion in the United States. There is essentially no precedent for a lone judge overruling the FDA's medical decisions, and pharmaceutical executives signed a letter Monday warning that the ruling could endanger other medications.

In appealing to the 5th U.S. Circuit Court of Appeals, the Biden administration said Kacsmaryk's "extraordinary and unprecedented order" should remain on hold while it challenges the decision.

"If allowed to take effect, the court's order would thwart FDA's scientific judgment and severely harm women, particularly those for whom mifepristone is a medical or practical necessity," the Justice Department wrote.

Kacsmaryk, an appointee of Donald Trump, issued his decision Friday but ruled it would not take effect for seven days -- meaning the end of this week barring another court stepping in.

Adding to the uncertainty was unresolved confusion Monday over a conflicting order by a different federal judge in the state of Washington, who within 20 minutes of Kacsmaryk's decision issued a separate ruling that directed U.S. authorities not to make any changes that would restrict access to the drug in at least 17 states where Democrats had sued.

Underlining that confusion, the Justice Department on Monday separately asked the federal court in Washington state for clarity, given the competing orders.

The abortion drug has been widely used in the U.S. since securing FDA approval. The other drug used for abortion medication in the United States is misoprostol, which is also used to treat other medical conditions and was not part of Kacsmaryk's decision.

Many providers must wait and see what happens in the courts between now and Friday before deciding what to do next, Jennifer Dalven, director of the American Civil Liberties Union's Reproductive Freedom Project, told reporters.

If the Texas court's ruling takes effect, some providers are prepared to pivot to a misoprostol-only regimen while others may transition to only surgical abortions.

"We don't know exactly what will happen," Dalven said. "What we do know is that there will be significant confusion and chaos as providers try to provide the best care they possibly can for their patients."

The lawsuit in Texas was filed by the Alliance Defending Freedom, which was also involved in the Mississippi case that led to Roe v. Wade being overturned. At the lawsuit's core is the allegation that the FDA's initial approval of mifepristone was flawed because it did not adequately review its safety risks.

Courts have long deferred to the FDA on issues of drug safety and effectiveness. But the agency's authority faces challenges in a post-Roe legal environment in which abortions are banned or unavailable in 14 states, while 16 states have laws specifically targeting abortion medications.

Among the pharmaceutical executives who signed the petition criticizing Kacsmaryk's ruling was Albert Bourla, CEO of the pharmaceutical giant Pfizer, which has produced the biggest-selling COVID-19 vaccine and treatment in the U.S.

The document warns that the decision diminishes the FDA's authority over drug approvals. A Pfizer spokeswoman verified for The Associated Press that Bourla signed the letter.

"If courts can overturn drug approvals without regard for science or evidence, or for the complexity required to fully vet the safety and efficacy of new drugs, any medicine is at risk for the same outcome as mifepristone," the letter states.

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Associated Press reporter Amanda Seitz in Washington and Tom Murphy in Indianapolis contributed to this report.