BEIJING, March 23 (Xinhuanet) -- The U.S. Navy is under fire from California state coastal regulators and environmental groups that filed separate lawsuits Thursday because of its decision to continue training exercises without precautions deemed nece ssary by opponents to protect marine life.

    The California Coastal Commission approved the exercises during a two-year period earlier this year only if the Navy took safeguards to protect marine mammals and sea turtles. Among the restrictions were avoiding coastal waters with a large whale and dolphin population and lowering sonar levels during periods of low visibility, when it's harder for ship personnel to spot sea life.

    The Navy sought the commission's approval for the training maneuvers, then did an about-face and said the commission lacked the authority to impose the restrictions.

    Commissioner Sara Wan argued the Navy's unwillingness to comply with the restrictions left the state with no choice but to file the federal lawsuit.

    "The Navy cannot simply arm-wave away the entire body of evidence ... that sonar can harm and kill marine mammals," Wan said.

    The commission is seeking a preliminary injunction against future sonar drills until the Navy agrees to the commission's limitations. It contends federal law gives it the power to limit the Navy's exercises to comply with a state law that protects coastal and marine resources.

    The Navy periodically conducts sonar drills along the East Coast, the Gulf Coast, Hawaii and the Pacific Northwest to practice hunting submarines in nearshore waters.

    Critics contend sonar has harmful effects on whales, possibly by damaging their hearing, and other marine mammals worldwide. A congressional report last year found the Navy's sonar exercises have been blamed for at least six cases of mass death and stranding among whales in the past decade.

    The Navy has said factors including pollution and starvation can cause marine animals to be beached.

    "We're disappointed with the decision to pursue litigation on this," Vice Adm. Barry Costello, commander of the U.S. Third Fleet, said in Honolulu. "But we're doing our training that's essential to the Navy to support our armed forces and we'll go forward and work with all the appropriate players on these lawsuits."

    In a separate lawsuit, a coalition of environmental groups led by the Santa Monica-based Natural Resources Defense Council faulted the Navy for failing to prepare an environmental impact statement on the planned drills. It's the fifth time the NRDC has sued the Navy over the sonar issue.

    (Agencies)