The agreement follows a Monday ruling by a US district court judge here that temporarily banned the navy from using the sonar in military exercises this week off the coast of Hawaii.

In her ruling, US District Judge Florence-Marie Cooper said there is "considerable convincing scientific evidence" that the high-intensity mid-frequency sonar, which the navy uses to detect quiet submarines, can kill and injure whales and other marine life.

Environmental groups sued the Navy over the issue last October. Plaintiffs included Jean-Michel Cousteau, son of French oceanographer Jacques-Yves Cousteau, and the Natural Resources Defense Council (NRDC), which includes former James Bond actor Pierce Brosnan as a member.

The groups charged the US navy with violating the National Environmental Policy Act by not fully studying the environmental impact of the sonar.

Judge Cooper said the environmental groups that won the court order were likely to succeed in their lawsuit.

Under the agreement, the US navy agreed not to use the sonar within 40 nautical kilometers (25 nautical miles) of the newly established Northwestern Hawaiian Islands Marine National Monument.

Navy sailors must also use underwater microphones to listen for marine mammals and report their presence, and conduct aerial surveillance for the animals during sonar drills.

The navy must also have one dedicated person and three others watching for whales from each of its ships during all sonar drills.

Richard Kendall, an attorney for the NRDC, described the agreement as "a significant step forward in the protection of our oceans."

The US navy still faces a separate lawsuit over using the sonar in other exercises, according to the NRDC.

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