Updated

Classified information about a U.S.-developed missile defense system was leaked from Japan's navy to students at a naval academy, a news report said Tuesday, as officials investigated security gaps in military information shared between the allies.

Investigators say the leak involved ship-to-air SM-3 interceptor missiles that are to be deployed on Japanese ships later this year, Kyodo News agency reported, citing unidentified officials.

Investigators are already looking into the alleged leak of information about the U.S.-developed high-tech Aegis radar system used in warships. That information was also shared between the United States and Japan.

"There are various investigations going on and I will not comment on individual cases," Chief Cabinet Secretary Yasuhisa Shiozaki told a regular news conference on Tuesday. Shiozaki did not specify whether investigators were looking into the SM-3 case.

Defense Minister Fumio Kyuma said he had not "heard anything" about the matter.

Hiromitsu Harada, a spokesman for Japan's Maritime Self-Defense Force, and Kanagawa police refused to comment.

Spokesmen for the U.S. Embassy in Tokyo and the U.S. Forces Japan likewise declined to comment on the report, saying it was policy not to discuss intelligence matters.

Japan and the U.S. have been accelerating plans for a joint missile defense system to counter threats from North Korean missiles and nuclear weapons. Deployment of the SM-3 interceptors on Japanese Aegis-equipped ships is part of the upgrade.

Investigators have also discovered leaks regarding a data system called "Link 16" used to share information between U.S. and Japanese military units, Kyodo reported.

The SM-3 information is believed to have been leaked to students at a naval academy, it said.

On Saturday, naval and local police raided the naval academy over the alleged leak of Aegis technology.

Local media said authorities believe that computer disks containing the classified data were illegally copied and circulated among dozens of students and instructors at the academy.

The case first surfaced in March when police found one of the disks at the home of a Japanese naval officer in Kanagawa during a separate investigation of his Chinese wife over her immigration status.

U.S. Defense Secretary Robert Gates expressed concern about the leak during talks with Kyuma last month in Washington.