The administration, fighting in court to defend its ban on the importation of assault weapons, moved Friday to ask an appeals court to overturn a federal judge's order releasing a gun dealer's shipment of semiautomatic rifles.

But despite arguing that the case revolved around "public safety issues of paramount public importance," the Justice Department failed to persuade U.S. District Judge William Acker of Birmingham, Ala., to stay his Thursday ruling pending an appeal.Acker's order directed the U.S. Customs Service to turn over 4,200 Austrian-made Steyr-Aug rifles to Gun South Inc. of Trussville, Ala.

Administration lawyers, arguing that the ruling actually affected 640,000 banned guns, hurried Friday afternoon to seek an emergency stay from the 11th U.S. Circuit Court of Appeals in Atlanta while the panel reviewed the case, said department spokeswoman Amy Brown.

In papers filed with Acker Friday, the department stressed that Director Stephen Higgins of the Bureau of Alcohol, Tobacco and Firearms concluded the guns were likely "to be used to kill and maim people" rather than for their stated sporting purposes.

"The specter of release of approximately 640,000 weapons which are unlikely to be recovered upon possible reversal of the district court's judgment highlights the potential for harm to the public," he said.

The Bush administration on March 14 suspended the importation of semiautomatic rifles not yet cleared by the Customs Service after a rash of violence nationwide, particularly involving use of AK-47 assault rifles. In one incident in January, five California schoolchildren were killed and 30 others wounded by a gunman with a semiautomatic rifle.

Acker, in the first court challenge to the temporary ban, ruled that the administration and national drug czar William Bennett improperly imposed it without consulting government experts or industry officials.

He criticized the ban as "obviously the product of a `hurry-up' skull session, if not a stampede reaction set off by Bennett."

Acker limited his ruling to weapons Gun South had ordered before being informed of the suspension, saying ATF agents had told the firm twice that the ban did not apply to permits issued previously and that Gun South put up $700,000 in cash for those weapons.

Rejecting the stay Friday, Acker ruled that Gun South "faces serious and irreparable injury if it is without a mandatory injunction, even for a short period of time."