A Chinese coastguard ship equipped with what appeared to be four gun turrets was sighted near disputed islands in the East China Sea, Japan's coastguard said on Wednesday.
Chinese coastguard vessels sail regularly near the islets, but a Japanese coastguard spokeswoman told Reuters it was the first time an armed Chinese coastguard ship had been spotted in the area.
The vessel, first sighted on Tuesday afternoon, was sailing 29 km (18 miles) off one of the contested islands as of 9:00 a.m. (8 p.m. ET on Tuesday) on Wednesday, Japan's coastguard said.
Sino-Japanese ties have long been mired in a bitter territorial dispute over the group of tiny, uninhabited islands, known as the Senkaku in Japan and Diaoyu in China.
Patrol ships and fighter jets from both sides regularly shadow each other near the islands, stoking concerns that an unintended collision or other incident could develop into a larger clash.
Japan said in 2013 that a Chinese navy vessel aimed fire control radar, normally used to aim weapons at a target, at a Japanese navy ship in the East China Sea, prompting Japan to protest.
