A Chinese navy survey ship on Thursday entered Japan's territorial waters near islands in Kagoshima Prefecture, the latest sighting of such a vessel in the area since February this year, the Defense Ministry said.

The vessel was spotted crossing into Japanese waters southwest of Yakushima island at around 10:00 a.m., the ministry said. The latest case marked the eighth entry by a Chinese survey ship into waters off Kagoshima since November 2021.

Japan has protested to China and conveyed its strong concern over the latest intrusion through diplomatic channels, the ministry said.

The vessel was confirmed to have left Japanese territorial waters west of Kuchinoerabu Island and headed toward the East China Sea at around 1 p.m., according to the ministry.

Chinese ships have repeatedly entered Japan's territorial waters or sailed through adjacent areas in recent years, particularly in the vicinity of the Senkaku Islands in the East China Sea.

The Japan-controlled, uninhabited islets are claimed by China under the name Diaoyu.

The islets are a continued source of tension between Japan and China, with the Japan Coast Guard separately saying Thursday that two Chinese coast guard vessels were spotted in territorial waters near them earlier the same day.

Survey vessels are often used to conduct research, such as determining underwater topography for submarine navigation.