LOS ANGELES (AP) — Conservationists on Wednesday blasted President Bush's decision to exempt the Navy from an environmental law so it can continue using high-power sonar in its training off Southern California — a practice they say harms whales and other marine mammals.

The president's action by itself won't allow the anti-submarine warfare training to go forward because an injunction is in place, but the Navy believes it will significantly strengthen its argument in court. A three-judge panel of the 9th U.S. Circuit Court of Appeals in San Francisco is expected to make a determination on the future of the Navy exercises on Friday.

The White House announced Bush signed the exemption Tuesday while traveling in the Middle East. In his memorandum, Bush said the Navy training exercises "are in the paramount interest of the United States" and its national security.

Peter Douglas, the executive director of the California Coastal Commission, called the exemption unprecedented in California.

"I'm not surprised at all," he said. "It's typical for this Republican administration to ignore environmental protections under the banner of fear."

Attorneys for the Natural Resources Defense Council said the group would file papers with the appeals court to challenge Bush's exemption.

"The president's action is an attack on the rule of law," said Joel Reynolds, director of the Marine Mammal Protection Project at the Natural Resources Defense Council in Santa Monica. "By exempting the Navy from basic safeguards under both federal and state law, the president is flouting the will of Congress, the decision of the California Coastal Commission and a ruling by the federal court."

A federal judge in Los Angeles issued a preliminary injunction this month requiring the Navy to create a 12-nautical-mile, no-sonar zone along the Southern California coast and to post trained lookouts to watch for marine mammals before and during exercises. Sonar would have to be shut down when mammals were spotted within 2,200 yards, under the order.

The court found that using mid-frequency active sonar violated the Coastal Zone Management Act and Bush exempted the Navy from a section of that act. Complying with the environmental law would "undermine the Navy's ability to conduct realistic training exercises that are necessary to ensure the combat effectiveness of carrier and expeditionary strike groups," Bush said.

Scientists say loud sonar can damage marine mammal brains and ears. Sonar may also mask the echoes some whales and dolphins listen for when they use their own natural sonar to locate food.

But much is still unknown about how sonar affects whales and other marine mammals. For example, the sound can hurt some species while not affecting others, and experts don't fully understand why.