The Food and Drug Administration on Thursday confirmed its previous finding that the anthrax vaccine being given to members of the U.S. military is safe and effective.

The drug has been at the center of a multiyear lawsuit that began when six members of the military challenged the Pentagon's use of a mandatory vaccination against anthrax in some military troops.

Published in the Federal Register Thursday, the FDA review on the Anthrax Vaccine Absorbed, or AVA, "determines AVA to be safe and effective and not misbranded."

FDA spokeswoman Julie Zawisza said the agency found no evidence to alter its previous determination that the vaccine was safe.

"We believe the vaccine is safe and effective for intended use, which would include (prevention of) inhalation anthrax," she said. The agency also received public comments about the vaccine, but Zawisza was unable to characterize them Thursday.

Since 1998, 1.2 million troops have been vaccinated against anthrax in six-shot regimens. Hundreds of service members had been punished or discharged for refusing them until U.S. District Judge Emmet Sullivan in December 2004 suspended the vaccinations after he found fault in the FDA's process for approving the drug. Several months later Sullivan said the Pentagon can resume giving vaccinations, but only to troops who volunteer for them.

Thursday's findings were the result a court-ordered review of the drug.

Earlier this month, the Bush administration appealed to reinstate mandatory inoculations for many military personnel.

Dr. William Winkenwerder, Assistant Secretary of Defense for Health Affairs, released a statement saying the military will continue to provide anthrax vaccines on a voluntary basis. Service members will still be able to refuse the vaccines.

"The threat of anthrax as a weapon remains real. It is very important to provide our service members with maximum protection against this threat, particularly when operating in certain areas of the world," he said.

He added that, "For people at increased risk of exposure, the benefits of the vaccine far outweigh the risks when all factors are considered. Vaccination against anthrax is the best round-the-clock protection available to protect our forces at risk."