Chinese and Japanese coast guard ships have faced off in waters around disputed islands in the East China Sea, both countries said on Tuesday.
China said it drove away several Japanese vessels that "illegally" entered territorial waters on Monday around the islands, which it calls Diaoyu, and it urged Japan to stop all "illegal activities" in the area.
Japan controls the islands and calls them the Senkaku.
Japan's coast guard said in a press release it ordered two Chinese coast guard vessels to leave the waters around the islands and maneuvered its ships to prevent them from approaching Japanese fishing boats.
The uninhabited area has long been a sticking point in ties between the two countries.