Tokyo, Dec. 7 -- Chinese fighter aircraft locked fire-control radar on Japanese military jets over international waters on Saturday, according to Japan's Defence Ministry, Japanese state media reported on Sunday.

The incident comes amidst simmering tensions between Tokyo and Beijing.

At a press briefing in the early hours of Sunday in Tokyo, Japanese Defence Minister Shinjiro Koizumi gave details of two episodes of a Chinese J-15 launched from a Chinese Liaoning aircraft carrier intermittently locking its radar on Japanese F-15 fighter planes over international waters southeast of Japan's Okinawa Prefecture, Kyodo reported.

Koizumi called the incidents "dangerous and extremely regrettable" and said Japan has lodged a strong protest and...