Japan's Prime Minister Shinzo Abe on Friday demanded Beijing apologise and admit that a Chinese frigate got a radar lock on a Japanese destroyer in international waters, a report said.
"We wish China to acknowledge it (the radar lock), apologise for it and make efforts to prevent it from recurring," he told the BS Fuji TV station, Jiji Press news agency reported.
His demand came after Beijing flatly denied Tokyo's accusation about the radar lock, the latest flare-up in a row between China and Japan over disputed islands in the East China Sea.
"We have confirmed visually and by photographs and other means such details as whether the radar was directed this way," the premier was quoted as saying.
Tokyo summoned China's envoy earlier Friday for the third time this year after Beijing's flat denial.
Vice Foreign Minister Chikao Kawai told Ambassador Cheng Yonghua the response was "totally unacceptable".
Tokyo says the radar lock, a procedure known as "painting" that is necessary to fire modern weapons systems, occurred last month.
Beijing for its part has accused Tokyo of hyping the "China threat" in a bid to manipulate world public opinion against its giant neighbour.
The radar incident marked the first time the two nations' navies have locked horns in the spat over the Tokyo-controlled Senkakus, which China claims as the Diaoyus.