FILE-- In this Feb. 26, 2014, file photo, Arizona Gov. Jan Brewer appears at a press conference at the Arizona Capitol in Phoenix. A federal appeals court ruled Tuesday that Arizona's regulations restricting abortion drugs appear to be an unconstitutional “undue burden on a woman’s right to abortion” and kept in place its injunction on them. (AP Photo/Ross D. Franklin, file)

SAN FRANCISCO - The nation's strictest rules on the use of abortion medication will continue to be blocked while a lawsuit against them plays out in court.

Arizona's regulations on the use of the most common abortion drugs are being challenged in court by Planned Parenthood Arizona, which says they pose an "undue burden" on women.

A three-judge panel of the 9th U.S. Circuit Court of Appeals said Tuesday it agreed with that argument, and decided to keep in place the injunction against the rules while the case against them continues in a lower federal court.

The regulations ban women from taking the most common abortion-inducing drug — RU-486 — after the seventh week of pregnancy. Women had been allowed to take the abortion pill through nine weeks of pregnancy.

They also require that the drug be administered only at the FDA-approved dosage and that both doses be taken at a clinic. The usual dosage is lower and now usually taken at home, decreasing the cost and chance of complications.

Planned Parenthood Arizona says the rules would force hundreds of women to undergo a surgical abortion while also placing a financial burden on women who live far from an abortion clinic. An attorney has argued the rules are also less effective and expose women to unnecessary side effects.

But Arizona attorneys say the rules are meant to protect women's health by mandating that drugs be used according to FDA-approved protocol. They say women will still have access to alternative types of abortions in Arizona.

At a hearing in May, two of the three judges expressed a willingness to continue the ban and questioned the constitutionality of the regulations enacted by the Arizona Legislature.

The Legislature approved the rules in 2012. A federal judge in Tucson where the case against them is being heard declined to temporarily block the rules a day before they were to take effect in April. Judge David C. Bury said in his ruling that although the new rules will make it more difficult for some women but that they aren't obstacles big enough to show that the rules should be blocked.

Planned Parenthood Arizona appealed to the 9th Circuit, which granted the injunction, saying women likely would suffer irreparable harm if the restrictions were allowed to take effect.

News from © The Associated Press, 2014