TOKYO — The U.S. Navy yesterday said a Pearl Harbor-based nuclear submarine was not responsible for a radiation leak detected and reported by the Japanese government in waters near Tokyo.

Last month, Japan's Ministry of Education, Culture, Sports, Science and Technology said that tests found radioactive material, including substances such as cobalt 60, in waters off Yokosuka as the USS Honolulu attack submarine left port on Sept. 14.

The ministry said the amount of radiation was so small that there was no danger to surrounding residents or the environment.

The Commander of the U.S. Naval Forces in Japan said in a statement today that its investigation had concluded there was no "deliberate" or "accidental" discharge of radioactivity from the Honolulu during its Yokosuka visit.

The Navy statement also said the leakage reported by Japan was extremely small — far lower than "the Japanese commercial nuclear power plant regulatory standard."

Japanese officials said last month that the USS Honolulu, based in Pearl Harbor, makes frequent stops in Japan, as do other nuclear submarines.

About 50,000 U.S. troops are based in Japan under a security pact between the two countries.

Washington plans to deploy the USS George Washington, a Nimitz-class nuclear-powered aircraft carrier, to Japan in 2008.