TOKYO • A Chinese naval intelligence ship was spotted off Japan's Boso Peninsula in Chiba prefecture several times from Wednesday to Saturday, according to a report from Kyodo news agency.
The vessel did not enter the country's territorial waters, Japan's Defence Ministry said, but added it is rare for a Chinese naval vessel to sail back and forth in that area near Tokyo.
Japan said it had conveyed to China its concern over the incident, and the ministry has begun investigating why the Chinese ship was sailing in the area, reported Kyodo.
Last week, a Chinese coast guard ship that appeared to be armed with several cannon entered what Tokyo regards as its territorial waters near disputed islands, the Japan Coast Guard said.
Japan and China routinely butt heads over ownership of the uninhabited East China Sea islets, as Chinese ships have sometimes approached them to back up Beijing's claims and test Japan's response.
It was, however, the first time that an apparently armed Chinese coast guard vessel had "entered the territorial waters near the Senkaku Islands", the Japan Coast Guard said. China refers to the islands as Diaoyu.