A Chinese navy vessel locked its weapon-targeting radar on a Japanese ship amid mounting tensions over a territorial row prompting Tokyo to protest.
Japanese Defence Minister Itsunori Onodera said the incident occurred on 30 January near islands claimed by both the nations in the East China Sea.
Onodera told reporters on Tuesday that something like fire-control radar was directed at a Japan Self-Defence Maritime escort ship in the sea.
According to the BBC, he said the move had prompted Tokyo to lodge a formal protest with Beijing.
The row, over islands known as Senkaku in Japan and Diaoyu in China, has escalated in recent months.
The minister said Japan's Yuudachi vessel and the Chinese frigate were about three kilometers away at the time, Japan's Kyodo News reports.
Asked about the delay in filing the protest, Onodera said it took the ministry until Tuesday to determine that fire-control radar had indeed locked on the Japanese ship.
He added that a Japanese military helicopter was also targeted with a similar type of radar by another Chinese frigate on 19 January.
He said that 'directing such radar is very abnormal. We recognise it would create a very dangerous situation if a single misstep occurred'.
Radars use radio waves to detect the intended target and then guide missiles or other weapons, the report added. (ANI)