A Chinese naval ship sailed in Japan's waters earlier this week off its southwestern prefecture of Kagoshima, the Defense Ministry said, as security tensions between the two countries have shown no signs of easing.

It was the first time since July 2017 that the ministry had confirmed and disclosed a Chinese naval vessel's intrusion into Japanese waters. It was the fourth time in total for such an incursion.

The Japanese government conveyed concern about the vessel's action to China through diplomatic channels, officials familiar with the matter said Friday.