The incident concerns Japan's claim that on Jan. 30 a Chinese frigate aimed its fire-control radar at a Japanese Maritime Self-Defense Force destroyer in the East China Sea, where the two countries are locked in a bitter territorial dispute over the Senkaku Islands. China has rejected the Japanese claim.
The incident has only led to further worsening of tensions over the dispute.
Kyodo News, citing official sources, reported the Japanese government had earlier considered providing China with the evidence, but later decided such a step would reveal its intelligence-gathering operations.
A Defense Ministry source told Kyodo Japan has frequency analysis data of radio waves the MSDF warship received from the Chinese ship, photos and footage at the time of the occurrence. However, the source said its disclosure poses "great risk in terms of defense as it would mean that Chinese military authorities would be looking at the MSDF's secrets concerning information-gathering operations."
Another source told Kyodo the evidence data also would disclose the "subtleties" of Japanese security.
The sources said the Japanese government will not officially announce its decision so as to keep its pressure on China.
The Chinese Foreign Ministry has accused Japan of "spreading false information."
Japan also has said in an earlier incident Jan. 19, a Chinese naval ship was suspected of having directed fire-control radar at an MSDF helicopter flying over the East China Sea.