China Coast Guard vessels have been passing by Japanese-claimed waters for weeks in the East China Sea and China’s warships have been edging near Japan’s southwestern islands over the past few days, Japanese officials said.

A fleet of four China Coast Guard vessels on Thursday passed just outside of the territorial waters of Japan-controlled islands, which Beijing and Taiwan also claim, for the 49th day in a row, the Japan Coast Guard said.

It said it warned China’s vessels against further approaching the Diaoyutai Islands (釣魚台群島) — known as the Senkakus in Japan.