A federal judge in Los Angeles banned the U.S. Navy from using high-powered sonar in nearly a dozen upcoming training exercises off Southern California, ruling yesterday that its use could "cause irreparable harm to the environment."

U.S. District Judge Florence-Marie Cooper issued the preliminary injunction after rejecting the Navy's request to dismiss a lawsuit brought by the Natural Resources Defense Council.

The Navy said it plans to appeal.

The court case is another setback for the Navy and its use of mid-frequency sonar, which has increasingly been challenged by environmental groups.

The latest court ruling does not affect Navy anti-submarine warfare exercises off Hawai'i, but several environmental organizations in May sued in federal court to block the Navy from planned exercises using high-volume sonar in Hawaiian waters.

A federal judge banned the Navy yesterday from using high-power sonar during a series of upcoming training exercises, ruling the technology can cause widespread damage to dozens of species of whales and marine mammals.